Exam

essay on biology

"Genetics and human problems"

11 "A" class student

Kirov Physics and Mathematics Lyceum

Ponomarev Andrey.

Kirov, 2000.

Plan.

o Introduction 3

o Milestones in the development of genetics 3

o Nucleic acids 8

o Genetic code 9

o Biosynthesis of proteins 10

o Chromosomal complex 10

o Human sex chromosomes 11

o Properties of the human genome: mutability 11

o Properties of the human genome: variability 14

o Discrete variability 14

o Continuous variability 15

o Environmental influence 15

o Sources of variability 16

o Hereditary diseases 17

o Hereditary metabolic diseases 28

o Lethal Genes 30

o Medical genetic counseling 31

o Genetic monitoring 34

o Conclusion 35

o References 37

Introduction.

Genetics is one of the main, most fascinating and at the same time complex disciplines of modern natural science. The place of genetics among the biological sciences and the special interest in it are determined by the fact that it studies the basic properties of organisms, namely heredity And variability .

As a result of numerous experiments in the field of molecular genetics, brilliant in their design and the finest in execution, modern biology has been enriched by two fundamental discoveries, which have already been widely reflected in human genetics, and partially carried out on human cells. This shows the inseparable connection between the successes of human genetics and the successes of modern biology, which is becoming more and more connected with genetics.

The first is the ability to work with isolated genes. It is obtained by isolating the gene in its pure form and synthesizing it. The significance of this discovery is difficult to overestimate. It is important to emphasize that different methods are used for gene synthesis, i.e. there is already a choice when it comes to such a complex mechanism as a person.

The second achievement is the proof of the inclusion of foreign information in the genome, as well as its functioning in the cells of higher animals and humans. Materials for this discovery were accumulated from different experimental approaches. First of all, these are numerous studies in the field of the virus-genetic theory of the onset of malignant tumors, including the detection of DNA synthesis on an RNA template. In addition, experiments with prophage transduction, stimulated by the idea of ​​genetic engineering, confirmed the possibility of the functioning of the genes of simple organisms in mammalian cells, including human cells.

It can be said without exaggeration that, along with molecular genetics, human genetics is one of the most progressive sections of genetics in general. Her research spans from the biochemical to the population level, to include the cellular and organismal levels.

But consider separately the history of the development of genetics.

The main stages in the development of genetics.

The origins of genetics, like any science, should be sought in practice. Genetics arose in connection with the breeding of domestic animals and the cultivation of plants, as well as with the development of medicine. Since man began to use the crossing of animals and plants, he was faced with the fact that the properties and characteristics of the offspring depend on the properties of the parent individuals chosen for crossing. By selecting and crossing the best descendants, from generation to generation, a person created related groups - lines, and then breeds and varieties with hereditary properties characteristic of them.

Although these observations and comparisons could not yet become the basis for the formation of science, the rapid development of animal husbandry and breeding, as well as crop and seed production in the second half of the 19th century, gave rise to an increased interest in the analysis of the phenomenon of heredity.

The development of the science of heredity and variability was especially strongly promoted by Charles Darwin's theory of the origin of species, which introduced the historical method of studying the evolution of organisms into biology. Darwin himself put a lot of effort into the study of heredity and variability. He collected a huge amount of facts, made a number of correct conclusions on their basis, but he failed to establish the laws of heredity. His contemporaries, the so-called hybridizers, who crossed various forms and looked for the degree of similarity and difference between parents and offspring, also failed to establish general patterns of inheritance.

Another condition that contributed to the formation of genetics as a science was advances in the study of the structure and behavior of somatic and germ cells. Back in the 70s of the last century, a number of cytological researchers (Chistyakov in 1972, Strasburger in 1875) discovered indirect somatic cell division, called karyokinesis (Schleicher in 1878) or mitosis (Flemming in 1882) . The constant elements of the cell nucleus in 1888, at the suggestion of Valdeyre, were called "chromosomes". In the same years, Flemming broke the entire cycle of cell division into four main phases: prophase, metaphase, anaphase and telophase.

Simultaneously with the study of somatic cell mitosis, studies were underway on the development of germ cells and the mechanism of fertilization in animals and plants. O. Hertwig in 1876 for the first time in echinoderms establishes the fusion of the nucleus of the spermatozoon with the nucleus of the egg. N.N. Gorozhankin in 1880 and E. Strasburger in 1884 established the same for plants: the first for gymnosperms, the second for angiosperms.

In the same van Beneden (1883) and others, the cardinal fact is revealed that in the process of development, germ cells, unlike somatic cells, undergo a reduction in the number of chromosomes exactly by half, and during fertilization - the fusion of the female and male nuclei - the normal number of chromosomes is restored , constant for each species. Thus, it was shown that a certain number of chromosomes is characteristic of each species.

So, these conditions contributed to the emergence of genetics as a separate biological discipline - a discipline with its own subject and methods of research.

The spring of 1900 is considered to be the official birth of genetics, when three botanists, independently of each other, in three different countries, at different objects, came to the discovery of some of the most important patterns of inheritance of traits in the offspring of hybrids. G. de Vries (Holland), on the basis of work with evening primrose, poppy, dope and other plants, reported "the law of splitting of hybrids"; K. Korrens (Germany) established patterns of splitting in corn and published the article "Gregor Mendel's law on the behavior of offspring in racial hybrids"; in the same year, K. Cermak (Austria) published an article (On artificial crossing in Pisum Sativum).

Science knows almost no unexpected discoveries. The most brilliant discoveries, creating stages in its development, almost always have their predecessors. This is what happened with the discovery of the laws of heredity. It turned out that the three botanists who discovered the pattern of splitting in the offspring of intraspecific hybrids merely “rediscovered” the patterns of inheritance discovered back in 1865 by Gregor Mendel and set forth by him in the article “Experiments on Plant Hybrids” published in the “Proceedings” of the Society of Naturalists in Brunn (Czechoslovakia).

G. Mendel developed methods for genetic analysis of the inheritance of individual traits of an organism on pea plants and established two fundamentally important phenomena:

1. signs are determined by individual hereditary factors that are transmitted through germ cells;

2. individual characteristics of organisms do not disappear during crossing, but are preserved in the offspring in the same form in which they were in the parent organisms.

For the theory of evolution, these principles were of cardinal importance. They uncovered one of the most important sources of variability, namely, the mechanism for maintaining the fitness of the traits of a species in a number of generations. If the adaptive traits of organisms, which arose under the control of selection, were absorbed, disappeared during crossing, then the progress of the species would be impossible.

All subsequent development of genetics has been associated with the study and extension of these principles and their application to the theory of evolution and selection.

From the established fundamental provisions of Mendel, a number of problems logically follow, which, step by step, are being resolved as genetics develops. In 1901, de Vries formulated the theory of mutations, which states that the hereditary properties and characteristics of organisms change in leaps and bounds - mutations.

In 1903, the Danish plant physiologist W. Johannsen published his work “On Inheritance in Populations and Pure Lines”, in which it was experimentally established that outwardly similar plants belonging to the same variety are hereditarily different - they constitute a population. The population consists of hereditarily different individuals or related groups - lines. In the same study, the existence of two types of variability in organisms is most clearly established: hereditary, determined by genes, and non-hereditary, determined by a random combination of factors acting on the manifestation of traits.

At the next stage in the development of genetics, it was proved that hereditary forms are associated with chromosomes. The first fact revealing the role of chromosomes in heredity was the proof of the role of chromosomes in sex determination in animals and the discovery of the 1:1 sex splitting mechanism.

Since 1911, T. Morgan with colleagues at Columbia University in the USA began to publish a series of works in which he formulated the chromosome theory of heredity. Experimentally proving that the main carriers of genes are chromosomes, and that genes are located linearly in chromosomes.

In 1922 N.I. Vavilov formulates the law of homological series in hereditary variability, according to which species of plants and animals related in origin have similar series of hereditary variability. Applying this law, N.I. Vavilov established the centers of origin of cultivated plants, in which the greatest variety of hereditary forms is concentrated.

In 1925, in our country, G.A. Nadson and G.S. Filippov on mushrooms, and in 1927 G. Möller in the USA on the Drosophila fruit fly obtained evidence of the influence of X-rays on the occurrence of hereditary changes. It was shown that the rate of mutations increases by more than 100 times. These studies have proved the variability of genes under the influence of environmental factors. Evidence of the influence of ionizing radiation on the occurrence of mutations led to the creation of a new branch of genetics - radiation genetics, the importance of which grew even more with the discovery of atomic energy.

In 1934, T. Painter, on the giant chromosomes of the salivary glands of Diptera, proved that the discontinuity of the morphological structure of chromosomes, expressed in the form of various disks, corresponds to the arrangement of genes in chromosomes, previously established by purely genetic methods. This discovery laid the foundation for the study of the structure and functioning of the gene in the cell.

In the period from the 1940s to the present, a number of discoveries (mainly on microorganisms) of completely new genetic phenomena have been made, which have opened up the possibilities of analyzing the structure of a gene at the molecular level. IN last years With the introduction of new research methods into genetics, borrowed from microbiology, we have come to unravel how genes control the sequence of amino acids in a protein molecule.

First of all, it should be said that it has now been fully proven that the carriers of heredity are chromosomes, which consist of a bundle of DNA molecules.

Quite simple experiments were carried out: from the killed bacteria of one strain, which had a special external feature, pure DNA was isolated and transferred to living bacteria of another strain, after which the multiplying bacteria of the latter acquired the feature of the first strain. Such numerous experiments show that it is DNA that is the carrier of heredity.

In 1953, F. Crick (England) and J. Watstone (USA) deciphered the structure of the DNA molecule. They found that each DNA molecule is made up of two polydeoxyribonucleic chains, spirally twisted around a common axis.

At present, approaches have been found to solving the problem of organizing the hereditary code and its experimental decoding. Genetics, together with biochemistry and biophysics, came close to elucidating the process of protein synthesis in a cell and the artificial synthesis of a protein molecule. This begins a completely new stage in the development of not only genetics, but of all biology as a whole.

The development of genetics to the present day is a continuously expanding fund of research on the functional, morphological and biochemical discreteness of chromosomes. A lot has already been done in this area, a lot has already been done, and every day the cutting edge of science is approaching the goal - unraveling the nature of the gene. To date, a number of phenomena characterizing the nature of the gene have been established. First, the gene in the chromosome has the property of self-reproducing (self-reproduction); secondly, it is capable of mutational change; thirdly, it is associated with a certain chemical structure of deoxyribonucleic acid - DNA; fourthly, it controls the synthesis of amino acids and their sequences in a protein molecule. In connection with recent studies, a new understanding of the gene as a functional system is being formed, and the effect of the gene on determining traits is considered in an integral system of genes - the genotype.

The opening prospects for the synthesis of living matter attract great attention of geneticists, biochemists, physicists and other specialists.

Nucleic acids.

Nucleic acids, like proteins, are essential for life. They represent the genetic material of all living organisms, down to the simplest viruses. The elucidation of the structure of DNA opened a new era in biology, as it made it possible to understand how living cells accurately reproduce themselves and how they encode the information necessary to regulate their life. Nucleic acids are made up of monomeric units called nucleotides. Long molecules are built from nucleotides - polynucleotides. A nucleotide molecule consists of three parts: a five-carbon sugar, a nitrogenous base, and phosphoric acid. The sugar in nucleotides is a pentose.

There are two types of nucleic acids - ribonucleic (RNA) and deoxyribonucleic (DNA). Both types of nucleic acids contain bases of four different types: two of them belong to the class of purines, others to the class of pyrimidines. The nitrogen contained in the rings gives the molecules their basic properties. Purines are adenine (A) and guanine (G), and pyrimidines are cytosine (C) and thymine (T) or uracil (U). Purines have two rings, while pyrimidines have one. RNA contains uracil instead of thymine. Thymine is chemically very close to uracil, more specifically 5-methyluracil.

Nucleic acids are acids because their molecules contain phosphoric acid. When a sugar combines with a base, a nucleoside is formed. The connection occurs with the release of a water molecule. For the formation of a nucleotide, another condensation reaction is required, as a result of which, a phosphoester bond arises between the nucleoside and phosphoric acid. Different nucleotides differ from each other in the nature of the sugars and bases that are part of them. The role of nucleotides in the body is not limited to serving as the building blocks of nucleic acids; some important coenzymes are also nucleotides or their derivatives.

Two nucleotides combine to form a dinucleotide by condensation. As a result, a phosphodiester bridge appears between the phosphate group of one nucleotide and the sugar of another. In the synthesis of polynucleotides, this process is repeated several million times. Phosphodiester bridges arise due to strong covalent bonds, and this imparts strength and stability to the entire nucleotide chain, which is very important, since this reduces the risk of DNA “breakdowns” during its replication.

RNA has two forms: transport (tRNA) and ribosomal (rRNA). They have a rather complex structure. The third form is information, or matrix, RNA (mRNA). All of these forms are involved in protein synthesis. mRNA is a single-stranded molecule formed on one of the DNA strands during transcription. During mRNA synthesis, only one strand of the DNA molecule is copied. The nucleotides from which mRNA is synthesized are attached to DNA in accordance with the rules of base pairing and with the participation of the RNA polymerase enzyme. The base sequence in mRNA is a complementary copy of the DNA chain - a template. Its length can be different, depending on the length of the polypeptide chain that it encodes. Most mRNA exists in the cell for a short time.

Ribosomal RNA is encoded by special genes located on several chromosomes. The sequence in rRNA is similar in all organisms. It is found in the cytoplasm, where it forms, together with protein molecules, cell organelles called ribosomes. Protein synthesis takes place on ribosomes. Here, the "code" contained in the mRNA is translated into the amino acid sequence of the polypeptide chain under construction. Groups formed by ribosomes - polyribosomes (polysomes) - make it possible to simultaneously synthesize several polypeptide molecules with the participation of one mRNA molecule.

Each amino acid has a specific tRNA, and all of them deliver the amino acids contained in the cytoplasm to the ribosomes. Thus, tRNAs play the role of links between the triplet code contained in mRNA and the amino acid sequence in the polypeptide chain. Since many amino acids are encoded by multiple triplets, the number of tRNAs is well over 20 (60 have already been identified). Each amino acid attaches itself to one of its tRNAs. As a result, aminoacyl is formed - tRNA, in which the binding energy between the terminal nucleotide A and the amino acid is sufficient so that a peptide bond can subsequently form with the carboxyl group of the neighboring amino acid.

Genetic code.

The sequence of bases in DNA nucleotides must determine the amino acid sequence of proteins. This relationship between bases and amino acids is the genetic code. Using four types of nucleotides, the parameters for the synthesis of protein molecules are recorded. The base triple code contains four different triplets. The proof of the triplet code was presented by F. Crick in 1961. For many amino acids, only the first letters are essential. One of the features of the genetic code is that it is universal. All living organisms have the same 20 amino acids and five nitrogenous bases.

At present, advances in molecular biology have reached such a level that it has become possible to determine the sequence of bases in entire genes. This is a major milestone in the development of science, since it is now possible to artificially synthesize entire genes. This has found application in genetic engineering.

Biosynthesis of proteins.

The only molecules that are synthesized under the direct control of the cell's genetic material are proteins (except for RNA). Proteins can be structural (keratin, collagen) or play a functional role (insulin, fibrinogen and, most importantly, enzymes responsible for the regulation of cellular metabolism). It is the set of enzymes contained in a given cell that determines what type of cells it will belong to. In 1961, two French biochemists Jacob and Monod, based on theoretical considerations, postulated the existence of a special form of RNA that plays the role of an intermediary in protein synthesis. Subsequently, this mediator was named mRNA.

Data obtained using various methods in experiments showed that the process of RNA synthesis consists of two stages. At the first stage (transcription), relatively weak hydrogen bonds between the complementary bases of polynucleotide chains are broken, which leads to the unwinding of the DNA double helix and the release of single strands. One of these strands is chosen as a template for constructing a complementary single mRNA strand. mRNA molecules are formed by binding free ribonucleotides to each other. The synthesized mRNA molecules carrying genetic information leave the nucleus and are directed to the ribosomes. After a sufficient number of mRNA molecules have been formed, transcription stops and the two strands of DNA in this region reconnect, restoring the double helix. The second stage is translation, which occurs on ribosomes. Several ribosomes can attach to an mRNA molecule like beads on a string, forming a structure called a polysome. The advantage of such a complex is that, in this case, the simultaneous synthesis of several polypeptide chains becomes possible on one mRNA molecule. As soon as a new amino acid has joined the growing polypeptide chain, the ribosome moves along the mRNA strands. The tRNA molecule leaves the ribosome and returns to the cytoplasm. At the end of translation, the polypeptide chain leaves the ribosome.

The human chromosome complex.

On Earth, there are no two completely identical people, with the exception of identical twins. The reasons for this diversity are not difficult to understand from the genetic point of view.

The number of chromosomes in humans is 46 (23 pairs). If we assume that the parents differ in each pair of chromosomes in only one gene, then the total number of possible genotypic combinations is 223. In fact, the number of possible combinations will be much greater, since the crossover between homologous chromosomes is not taken into account in this calculation. Therefore, from the moment of conception, each person is genetically unique and unrepeatable.

Human sex chromosomes.

Genes located on the sex chromosomes are called sex-linked. The phenomenon of linkage of genes located on the same chromosome is known as Morgan's law. There is a region on the X chromosome for which there is no homologue on the Y chromosome. Therefore, in a male individual, the traits determined by the genes of this site appear even if they are recessive. This particular form of linkage explains the inheritance of sex-linked traits such as color blindness, early baldness, and hemophilia in humans. Hemophilia is a sex-linked recessive trait in which blood clotting is impaired. The gene that determines this process is located in the region of the X chromosome that does not have a homologue and is represented by two alleles - a dominant normal and a recessive mutant.

Female individuals heterozygous for recessive or dominant are called carriers of the corresponding recessive gene. They are phenotypically normal, but half of their gametes carry the recessive gene. Despite the presence of the normal gene in the father, the sons of carrier mothers have a 50% chance of suffering from hemophilia.

Properties of the human genome: Mutability.

The variability of organisms is one of the main factors of evolution. It serves as the main source for the selection of forms most adapted to the conditions of existence.

Change is a complex process. Usually biologists divide it into hereditary and non-hereditary. Hereditary variability includes such changes in the signs and properties of organisms that do not disappear during sexual reproduction and persist in a number of generations. Non-hereditary variability - modifications, or fluctuations, include changes in the properties and characteristics of an organism that occur in the process of its individual development under the influence of environmental factors that have developed in a specific way for each individual, and are not preserved during sexual reproduction.

Hereditary variability is a change in the genotype, non-hereditary - a change in the phenotype of the organism.

The term "mutation" was first proposed by Hugh de Vries in his classic work The Mutation Theory (1901-1903). Mutation he called the phenomenon of a spasmodic, discontinuous change in a hereditary trait. The main provisions of the theory of G. de Vries still have not lost their significance, and therefore they should be given here:

1) mutation occurs suddenly, without any transitions;

2) the new forms are completely constant, i.e. resistant;

3) mutations, unlike non-hereditary changes (fluctuations), do not form continuous series, do not group around an average type (mode). Mutations are qualitative changes;

4) mutations go in different directions, they can be both beneficial and harmful;

5) detection of mutations depends on the number of individuals analyzed to detect mutations.

6) The same mutations can occur repeatedly.

However, G. de Vries made a fundamental mistake by opposing the theory of mutations to the theory of natural selection. He incorrectly believed that mutations could immediately give rise to new species adapted to the environment, without the participation of natural selection. In fact, mutations are only a source of hereditary changes that serve as material for natural or artificial selection.

the term "gene" was first used to denote a hereditary trait by Johansen in 1911. The relationship between a gene and a protein, the structure of which is determined by the structure of the gene, was first formulated as the "1 gene - 1 enzyme" hypothesis by Beadle and Tatum. Direct evidence that human gene mutations cause a change in the primary structure of proteins was obtained in 1949 by Pauling in the study of hereditary hemoglobinopathies. Examining the primary structure of hemoglobin isolated from the erythrocytes of patients with sickle cell anemia Pauling showed that the mobility of abnormal hemoglobin in electric field(electrophoresis) changed compared to normal. Further, he found that this effect is associated with the replacement of the amino acid valine with glutamic acid. This discovery began new era discoveries in human biochemical genetics of hereditary metabolic diseases. They are caused by mutations in genes that produce proteins with an abnormal structure, which leads to a change in their functions.

Most organisms store genetic information in DNA - a linear polymer consisting of 4 different monomeric units - deoxyribonucleotides, which are linked to each other in a chain by phosphodiester bonds. As was proven by Watson and Crick, a typical DNA molecule consists of 2 plynucleotide strands, each containing several thousand to several million molecules. Each nucleotide in one strand is specifically hydrogen bonded to a nucleotide in another strand. Only 2 types of nucleotide pairing are found in DNA: deoxyadenosine monophosphate with thymidine monophosphate (A-T pair) and deoxyguanidine monophosphate with deoxycytidine monophosphate (G-C pair). Thus, the nucleotide sequence of one strand exactly determines the sequence in the other, and both strands are complementary to each other. The sequence of the four nucleotides along a polynucleotide chain varies among the DNA of unrelated organisms and is the molecular basis of their genetic divergence. Because most hereditary characteristics are stably passed down from parent to offspring, the nucleotide sequence in the DNA must be exactly copied when an organism reproduces. This takes place in both circuits. The nucleotide sequence, and hence the genetic information, is conserved during the process of replication. Because each nucleotide in the daughter strands is specifically paired with a complementary nucleotide in the parent or template strands before the polymerization process takes place. The DNA of higher organisms is regularly packaged into a structure called chromosomes, made up of nucleoprotein units (nucleosomes). Chromosomes are separated from all other cellular components by the nuclear membrane. Each of the nucleosomal elements consists of four, sometimes five, protein subunits called histones, which form a rod structure around which approximately 140 base pairs of genomic DNA are "wound". The structure of histones is characterized by high conservatism in the kingdom of eukaryotes. The double stranded model of DNA defines the way in which genes can be replicated to pass on to offspring. The replication process is complex, but conceptually simple. Two strands of DNA are separated and each is copied by a series of enzymes that insert complementary bases opposite each base on the original (parent) DNA strand. Thus, two identical double helixes are formed from one - this is the process of replication. DNA "makes" RNA, this process is called transcription, and RNA "makes" protein, this process is called translation. The sequence of the base in a specific gene ultimately dictates the sequence of amino acids in a specific protein; this collinearity between the DNA molecule and the protein is achieved through the genetic code. Four types of DNA bases assembled in groups of three form a triplet, each of which forms a code word, or codon, which determines the inclusion of one amino acid in the structure of the encoded protein, in this way the inclusion of each of the 20 amino acids that occur in proteins is determined. 64 different triplets exist for 20 amino acids, which determine the properties of the genetic code. Thus, most amino acids are defined by more than one codon, but each codon is completely specific.

Although at present the question of the nature of the gene has not been completely elucidated, a number of general patterns of gene mutation have nevertheless been firmly established. Gene mutations occur in all classes and types of animals, higher and lower plants, multicellular and unicellular organisms, bacteria and viruses. Mutational variability as a process of qualitative spasmodic changes is universal for all organic forms.

Properties of the human genome: Variability.

Variability is the whole set of differences in one or another trait between organisms belonging to the same natural population or species. The astonishing morphological diversity of individuals within any species caught the attention of Darwin and Wallace during their travels. The natural, predictable nature of the transmission of such differences by inheritance served as the basis for Mendel's research. Darwin established that certain traits can develop as a result of selection, while Mendel explained the mechanism that ensures the transmission from generation to generation of traits for which selection is made.

Mendel described how hereditary factors determine the genotype of an organism, which in the process of development manifests itself in the structural, physiological and biochemical features of the phenotype. If the phenotypic expression of any trait is ultimately determined by the genes that control that trait, then the degree of development of certain traits can be influenced by the environment.

The study of phenotypic differences in any large population shows that there are two forms of variation - discrete and continuous. To study the variability of a trait, such as height in humans, it is necessary to measure that trait in a large number of individuals in the population under study. The measurement results are presented in the form of a histogram reflecting the frequency distribution of various variants of this trait in the population. On fig. Figure 4 shows typical results obtained from such studies and clearly demonstrates the difference between discrete and continuous variability.

Discrete variability

Some traits in a population are represented by a limited number of variants. In these cases, the differences between individuals are clearly expressed, and intermediate forms are absent; such features include, for example, blood types in humans, the length of wings in Drosophila, melanistic and light forms in birch moths (Biston betularia), primrose column length (Primula) and sex in animals and plants. Traits characterized by discrete variability are usually controlled by one or two major genes, which may have two or more alleles, and environmental conditions have relatively little effect on their phenotypic expression.

Since discrete variability is limited to some well-defined features, it is also called quality variability as opposed to quantitative, or continuous, variability.

Picture 1. Histograms reflecting the distribution of frequencies in the case of discontinuous (A) and non-discontinuous (B) variability.

Continuous variability

In many ways, the population shows a complete series of transitions from one extreme to another without any breaks. The most striking features of frozen are such features as mass (weight), linear dimensions, shape and color of the organism as a whole or its individual parts. The frequency distribution for a trait exhibiting continuous variability corresponds to bell curve. Most members of the population fall into the middle part of the curve, and at its ends, corresponding to the two extreme values ​​of this trait, there is an approximately equal (very small) number of individuals. Characters that are characterized by continuous variability are due to the combined effect of many genes (polygenes) and environmental factors. Each of these genes individually has a very small effect on the phenotype, but together they create a significant effect.

Environmental influence

The main factor that determines any phenotypic trait is the genotype. The genotype of an organism is determined at the moment of fertilization, but the degree of subsequent expression of this genetic potential largely depends on external factors affecting the organism during its development. So, for example, the long-stemmed pea variety used by Mendel usually reached a height of 180 cm. However, for this he needed the appropriate conditions - lighting, water supply and good soil. In the absence of optimal conditions (in the presence of limiting factors) the tall stem gene could not fully show its effect. The effect of the interaction of the genotype and environmental factors was demonstrated by the Danish geneticist Johansen. In a series of experiments on dwarf beans, he selected the heaviest and lightest seeds from each generation of self-pollinating plants and planted them to produce the next generation. Repeating these experiments over several years, he found that within a "heavy" or "light" breeding line, the seeds differed little in average weight, while the average weight of seeds from different lines varied greatly. This suggests that the phenotypic manifestation of a trait is influenced by both heredity and the environment. Based on these results, continuous phenotypic variability can be defined as "the cumulative effect of varying environmental factors acting on a variable genotype". In addition, these results show that the degree of heritability of a given trait is determined primarily by the genotype. As for the development of such purely human qualities as individuality, temperament, and intelligence, judging by the available data, they depend on both hereditary and environmental factors, which, interacting to varying degrees in different individuals, affect the final expression of the trait. It is these differences in these and other factors that create phenotypic differences between individuals. We do not yet have data that would firmly indicate that the influence of some of these factors always prevails, but the environment can never push the phenotype beyond the limits determined by the genotype.

Sources of variability

It must be clearly understood that the interaction between discrete and continuous variability and the environment makes it possible for two organisms to exist with an identical phenotype. The mechanism of DNA replication during mitosis is so close to perfection that the possibilities of genetic variability in organisms with asexual reproduction are very small. Therefore, any apparent variability in such organisms is almost certainly due to environmental influences. As for organisms that reproduce sexually, they have ample opportunities for the emergence of genetic differences. Almost unlimited sources of genetic variability are two processes that occur during meiosis:

1. Reciprocal gene exchange between chromate dumps of homologous chromosomes, which can occur in prophase 1 of meiosis. It creates new linkage groups, i.e. serves as an important source of genetic recombination of alleles .

2. The orientation of pairs of homologous chromosomes (bivalents) in the equatorial plane of the spindle in metaphase I of meiosis determines the direction in which each member of the pair will move in anaphase I. This orientation is random. During metaphase II, the pairs of chromatids again orient themselves randomly, and this determines which of the two opposite poles one or another chromosome will go to during anaphase II. Random orientation and subsequent independent divergence (segregation) of chromosomes makes possible a large number of different chromosome combinations in gametes; this number can be calculated.

The third source of variability in sexual reproduction is that the fusion of male and female gametes, resulting in the union of two haploid sets of chromosomes in the diploid zygote nucleus, occurs in a completely random way (at least in theory); any male gamete has the potential to fuse with any female gamete.

These three sources of genetic variation provide the constant shuffling of genes that underlies the ongoing genetic change. The environment influences the whole range of phenotypes thus obtained, and those best adapted to the environment succeed. This leads to changes in the frequencies of alleles and genotypes in the population. However, these sources of variability do not give rise to large changes in the genotype, which, according to evolutionary theory, are necessary for the emergence of new species. Such changes result from mutations.

Hereditary diseases (diagnosis, prevention, treatment)

The well-known general position about the unity of internal and external in the development and existence of normal and diseased organisms does not lose its significance in relation to hereditary diseases transmitted from parents to children, no matter how such diseases may seem to be predetermined by pathological hereditary inclinations. However, this provision requires a more detailed analysis, since it is not so unambiguous in relation to various forms of hereditary diseases and at the same time is applicable to a certain extent to such forms of pathology that seem to be caused only by pathogenic environmental factors. Heredity and environment turn out to be etiological factors or play a role in the pathogenesis of any human disease, but their share in each disease is different, and the greater the proportion of one factor, the less the other. All forms of pathology from this point of view can be divided into four groups, between which there are no sharp boundaries.

The first group consists of hereditary diseases proper, in which the pathological gene plays an etiological role, the role of the environment is to modify only the manifestations of the disease. This group includes monogenic diseases (such as, for example, phenylketonuria, hemophilia), as well as chromosomal diseases.

The second group is also hereditary diseases caused by a pathological mutation, but their manifestation requires a specific environmental impact. In some cases, such a "manifesting" effect of the environment is very obvious, and with the disappearance of the effect of the environmental factor, clinical manifestations become less pronounced. These are the manifestations of HbS hemoglobin deficiency in its heterozygous carriers at a reduced partial pressure of oxygen. In other cases (for example, with gout), for the manifestation of a pathological gene, a long-term adverse effect of the environment (nutritional features) is necessary.

The third group is the vast majority of common diseases, especially diseases of mature and old age (hypertension, gastric ulcer, most malignant tumors, etc.). The main etiological factor in their occurrence is the adverse effect of the environment, however, the implementation of the factor depends on the individual genetically determined predisposition of the organism, and therefore these diseases are called multifactorial, or diseases with a hereditary predisposition. It should be noted that different diseases with a hereditary predisposition are not the same in the relative role of heredity and environment. Among them, one could single out diseases with a weak, moderate and high degree of hereditary predisposition.

The fourth group of diseases is a relatively few forms of pathology, in the occurrence of which the environmental factor plays an exceptional role. Usually this is an extreme environmental factor, in relation to which the body has no means of protection (injuries, especially dangerous infections). Genetic factors in this case play a role in the course of the disease and influence its outcome.

Let's take a closer look at these four groups.

TO chromosomal diseases include forms of pathology that are clinically expressed by multiple malformations, and as a genetic basis, they have deviations from the normal content of the amount of chromosomal material in the cells of the body, i.e. due to genomic or chromosomal mutations.

Most chromosomal diseases are sporadic arising anew as a result of a genomic (chromosomal) mutation in the gamete of a healthy parent or in the first divisions of the zygote, and not inherited in generations, which is associated with a high mortality of patients in the pre-reproductive period. The phenotypic basis of chromosomal diseases is disorders of early embryonic development. Therefore, pathological changes are formed even in the prenatal period of development of the organism and either cause the death of the embryo or fetus, or create the main clinical picture of the disease already in the newborn. The role of chromosomal pathology in prenatal death of embryos or fetuses in humans is great. On average, about 40% of diagnosed spontaneous abortions are due to a chromosomal imbalance. About 6% of all stillborns have chromosomal changes. For every 1,000 live births, 3-4 have chromosomal disorders. If all cases of multiple malformations among newborns are taken as 100%, then 35-40% will be caused by a violation of the state of the chromosomes.

All chromosomal diseases on this basis can be divided into two large groups: caused by a change in the number of chromosomes while maintaining the structure of the latter (genomic mutations) and caused by changes in the structure of the chromosome (chromosomal mutations). In humans, all known types of mutations of both types have been described.

Numerical violations may consist in a change in the ploidy of the chromosome set and in the deviation of the number of chromosomes from the diploid one for each of their pairs in the direction of decreasing (monosomy) or increasing (polysemy). Genomic mutations on individual chromosomes are numerous; they make up the bulk of chromosomal diseases. Complete monosomy is observed on the X chromosome, leading to the development of Shereshevsky-Turner syndrome.

This syndrome develops with complete X-monosomy, when all or most of the cells have a chromosome set. K Clinical manifestations of this syndrome are the absence in women of the usual secondary sexual characteristics, short stature, close nipples, skeletal disorders, infertility, and various defects of internal organs.

The most fully studied trisomy on the 21st chromosome or, as it is also called, Down's disease. This anomaly, named after the doctor who first described it in 1866, is not caused by a chromosome mismatch.

Symptoms include delay mental development, reduced resistance to disease, congenital heart anomalies, a short, stocky torso and thick neck, as well as characteristic skin folds over the inner corners of the eyes, which creates resemblance with representatives of the Mongoloid race. Down syndrome and other similar anomalies are more common in children born to older women. The exact reason for this is unknown, but it seems to be related to the age of the mother's eggs. The number of X chromosomes in an individual can reach up to 5 while maintaining its viability.

Structural rearrangements of chromosomes, whatever type they may be, cause developmental disorders of the organism due to or lack of part of the material on a given chromosome (partial monosomy) or its excess (partial trisomy).

As an example one can give X-polysomy in the absence of a Y chromosome. Such organisms have a chromosome set of 47,XXX, and although outwardly women look normal and are fertile, they have mental retardation.

In Klinefelter's syndrome (47, XXY), the male has some secondary female gender characteristics, is infertile, the testicles are poorly developed, there is little facial hair, sometimes mammary glands develop, usually a low level of mental development.

With a chromosome set of 47.XYU, men are tall, have a different level of mental development, sometimes have psychopathic features or show a tendency to minor offenses.

Gene diseases are divided into two large groups: diseases with a clarified primary biochemical defect and diseases with an unexplained primary biochemical defect. The first group includes hereditary diseases of metabolism, protein biosynthesis, enzymes.

An example of hereditary defects in carbohydrate metabolism is galactosemia. One of the ways of exchanging monosaccharides in the body is the conversion of 0-galactose, which enters the body with food (it is formed in the intestine during the enzymatic hydrolysis of food lactose), into 0 "glucose. The conversion process consists of several stages and can be interrupted if the enzyme galacteo-1 is insufficient -phosphate uridyltransferae.Most often, the mutation leads to insufficient activity of the enzyme (10-12% of the normal level).The biochemical pathogenesis of the disease includes the accumulation of galactose in various tissues and in the blood, which leads to impaired use of glucose in the liver, kidneys and brain.Galactosemia occurs among newborns with a frequency of 1 in 35-150 thousand births.The disease develops after birth when the infant is fed, since lactose, a source of non-metabolized galactose, is supplied with milk.As a result, the child develops vomiting and diarrhea, leading to dehydration, and the gradual development of mental retardation on background of general dystrophy If, with the help of an appropriate diet, which provides for the complete exclusion of milk sugar, the child recovers, then with age, a second metabolic pathway for the conversion of galactose into glucose appears - with the participation of the enzyme uridyltransferase.

Hereditary aminoacidopathies (hereditary defects in amino acid metabolism) constitute the largest group of hereditary metabolic defects. By the beginning of 1985, their list included about 60 different nosological units, and although each of them is rare (1:20,000 - 1:100,000 newborns), in total they make up a significant part of hereditary metabolic defects.

Phenylketonuria. Clinically, this disease was first described in 1934, but only 19 years later it was found that this hereditary defect is associated with a deficiency of phenylalanine-4-hydroxylaea. Normally, excess phenylalanine, which comes from food and is not used for protein synthesis, is converted into tyrosine with the help of this enzyme. In patients with phenylketonuria, this amino acid accumulates in the blood. An increase in the level of phenylalanine in itself is not dangerous, but it stimulates unusual reactions, as a result of which keto derivatives of phenylalanine accumulate in the body. They cause damage to the nervous tissue in newborns and the development mental retardation further. Therefore, if the presence of this disease is detected in time and phenylalanine is excluded from food, the child will develop normally. There are several methods for diagnosing phenylketonuria. The most widely used microbiological tests.

Vitamins act as cofactors, prosthetic groups, and many enzymes. Their insufficient intake with food sharply reduces the activity of the corresponding metabolic processes. The resulting diseases are called avitaminosis and are easily treated by introducing the missing vitamins into the body. However, there are vitamin-independent beriberi, in which such measures have no effect. The causes of such diseases, and they are usually hereditary, have been uncovered after careful study of the metabolism of vitamins. Before acting as a coenzyme, the vitamin must be extracted from the intestines with special transport proteins and transported into the bloodstream. There it undergoes enzymatic modification and only then can it bind to the apoenzyme (if its structure is not changed), turning it into an active enzyme. Each of the genes encoding the proteins responsible for these transformations can be inactivated by a corresponding mutation. These genetic disorders give rise to diseases, for the treatment of which it is necessary to introduce ready-made coenzymes into the body. The development of treatments should be based on an accurate knowledge of the metabolic pathways of a given vitamin. The most difficult situation occurs when the apoenzyme is damaged. Currently, there are no effective ways to cope with such a pathology.

An example of hereditary defects in circulating proteins is sickle cell anemia. The protein part of any human hemoglobin (Hb) consists of two globin chains, each built from two polypeptide chains. Human hemoglobin is made up of two alpha and two beta chains. In sickle cell anemia, the valine at the beta position is replaced by glutalic acid. This substitution causes a reduced solubility of hemoglobin. Heterozygous HbS carriers are clinically healthy under normal conditions, since the blood also contains normal HbA; anomaly begins to manifest itself only under conditions reduced pressure(in the mountains). Homozygotes develop a characteristic pattern of chronic anemia with circulatory disorders and thrombosis from an early age. Hemoglobin HbS is often found in the population of regions where malaria is common, as it is insensitive to malarial plasmodium.

An example of a hereditary disease with an unexplained primary biochemical defect is achondroplasia. It is an example of a hereditary disease with a well-established dominant mode of inheritance. However, due to the sharply reduced ability of patients to have offspring, in almost 80-95% of cases this disease is associated with new emerging mutations.

Achondroplaea is one of the hereditary diseases of the skeletal system; its clinical picture is due to abnormal growth and development of cartilage tissue, mainly in the epiphyses of tubular bones and the base of the skull. Nothing is known about the biochemical nature of this disease, except for information about various deviations in the activity of a number of enzymes, the significance of which remains unclear.

The pathology of the growth of these bones determines the characteristic clinical picture, which is completely resolved in patients at puberty: 1) short stature (usually up to 120 cm) while maintaining a normal body length; 2) macrocephaly, tuberous medulla and characteristic face; 3) a sharp shortening of the upper and lower limbs, especially due to the femur and humerus, with their deformation and thickening.

Schizophrenia is a multifactorial or hereditary disease. It occupies a leading place among endogenous functional psychoses in frequency (more than 1%). The family nature of the incidence of schizophrenia and the participation of hereditary factors in its etiology has long been beyond doubt, however, as for other diseases with a hereditary predisposition, the genetic nature of the predisposition remains not fully deciphered. In recent years, the genetic patterns of schizophrenia have been actively studied by Soviet researchers under the leadership of M. E. Vartanyan, and these studies continue to this day.

As already emphasized, with the development of medicine, hereditary diseases make up an increasing share in the general pathology of a person. Most hereditary diseases have a chronic course, as a result of which the repeated appeal of such patients is high. At the same time, as the analysis of the contingent of patients shows, hereditary forms are not always diagnosed even in clinical conditions. To a certain extent, this is understandable, since the diagnosis of hereditary pathology is a very complex and time-consuming process.

Difficulties in diagnosis are primarily due to the fact that the nosological forms of hereditary diseases are very diverse (about 2000) and each of them is characterized by a wide variety of clinical presentations. So, in the group of nervous diseases, more than 200 hereditary forms are known, and in dermatology there are more than 250 of them. Some forms are extremely rare, and the doctor may not meet them in his practice. Therefore, he must know the basic principles that will help him suspect rare hereditary diseases, and after additional consultations and examinations, make an accurate diagnosis.

Diagnosis of hereditary diseases is based on clinical, paraclinical and special genetic examination data.

In a general clinical examination of any patient, the diagnosis should be completed by one of three conclusions:

1. a clear diagnosis of a non-hereditary disease;

2. clearly diagnosed hereditary disease;

3. there is a suspicion that the underlying or concomitant disease is hereditary.

The first two conclusions make up the bulk of the examination of patients. The third conclusion, as a rule, requires the use of special additional examination methods, which are determined by a geneticist.

A complete clinical examination, including a paraclinical examination, is usually sufficient to diagnose an inherited disorder such as achondroplaea.

In cases where the patient has not been diagnosed and it is necessary to clarify it, especially if a hereditary pathology is suspected, the following special methods are used:

1. A detailed clinical and genealogical examination is carried out in all cases when a hereditary disease is suspected during the initial clinical examination. It should be emphasized here that we are talking about a detailed examination of family members. This examination ends with a genetic analysis of its results.

2. Cytogenetic examination can be carried out in parents, sometimes in other relatives and the fetus. The chromosome set is studied if a chromosomal disease is suspected to clarify the diagnosis. An important role of cytogenetic analysis is prenatal diagnosis.

3. Biochemical methods are widely used in cases where there is a suspicion of hereditary metabolic diseases, those forms of hereditary diseases in which a defect in the primary gene product or a pathogenetic link in the development of the disease has been accurately established.

4. Immunogenetic methods are used to examine patients and their relatives in case of suspected immunodeficiency diseases, in case of suspected antigenic incompatibility between mother and fetus, in establishing true parenthood in cases of medical genetic counseling, or to determine hereditary predisposition to diseases.

5. Cytological methods are used to diagnose a still small group of hereditary diseases, although their possibilities are quite large. Cells from patients can be examined directly or after cultivation by cytochemical, radioautographic and other methods.

6. The gene linkage method is used in cases where there is a case of a disease in the pedigree and it is necessary to decide whether the patient has inherited the mutant gene. This must be known in cases of an erased picture of the disease or its late manifestation.

For a long time, the diagnosis of a hereditary disease remained as a doom to the patient and his family. Despite the successful deciphering of the formal genetics of many hereditary diseases, their treatment remained only symptomatic. For the first time, S. N. Davidenkov, back in the 30s, pointed out the fallacy of the point of view about the incurability of hereditary diseases. It proceeds from the recognition of the role of environmental factors in the manifestation of hereditary pathology. However, the lack of information about the pathogenetic mechanisms of the development of diseases at that time limited the possibilities of developing methods, and all attempts, despite the correct theoretical principles, remained empirical for a long time. At present, thanks to the successes of genetics in general (all its sections) and the significant progress in theoretical and clinical medicine, it can be argued that many hereditary diseases are already successfully treated. General approaches to the treatment of hereditary diseases remain the same as approaches to the treatment of diseases of other origins. Three approaches can be distinguished here: symptomatic, pathogenic, etiological.

Symptomatic treatment used for all hereditary diseases, even where there are methods of pathogenic therapy. For many forms of pathology, symptomatic treatment is the only one.

Symptomatic drug therapy is the most commonly used technique, varied depending on the forms of hereditary diseases: the use of analgin for hereditary forms of migraine, specific tranquilizers for mental illness, pilocarpine for glaucoma, special ointments for skin diseases, etc. The success of this section of therapy is associated with progress in pharmacology, providing an ever wider choice of drugs. On the other hand, deciphering the pathogenesis of each disease makes it possible to understand the cause of the onset of symptoms, and on this basis, drug correction of symptoms becomes more subtle. An example is the symptomatic treatment of cystic fibrosis.

When it was found that with cystic fibrosis, very thick mucus is formed in the ducts of the endocrine glands of the bronchi, to alleviate the condition, such patients began to prescribe substances that thin the mucus (mucolytic substances).

Surgical symptomatic treatment occupies an important place in the treatment of hereditary pathology, especially expressed in the form of congenital malformations or systemic skeletal lesions. For example, blood transfusion in thalassemia, plastic surgery for upper lip cleft, cataract removal are all examples of symptomatic treatment.

In general, the types of surgical care for patients with hereditary pathology can be of three types: removal (tumors, etc.); correction (non-closure of the upper lip, congenital heart defects, etc.); transplantation (combined immune deficiency, etc.).

In some cases, surgical care goes beyond symptomatic treatment, approaching pathogenetic in nature.

many kinds physical methods treatments (thermotherapy, various types of electrotherapy, etc.) are used for hereditary diseases nervous system, hereditary metabolic diseases, diseases of the skeleton. Symptomatic treatment can also include X-ray radiation exposure for hereditary tumors before and after surgery.

The possibilities of symptomatic treatment for many diseases are far from being exhausted, especially in the field of drug, dietary and surgical care.

Treatment of many diseases according to the principle of intervention in disease pathogenesis always more effective than symptomatic. However, it should be understood that none of the currently existing methods eliminates the cause of the disease, since it does not restore the structure of damaged genes. The action of each of them lasts a relatively short time, so the treatment should be continuous. In addition, one has to admit the limited possibilities of modern medicine: many hereditary diseases are still not amenable to effective relief. In this regard, special hopes are placed on the use of genetic engineering methods to introduce normal, unchanged genes into the cells of a sick person. In this way, it will be possible to achieve a radical cure for this patient, but, however, this is a matter for the future.

Currently, there are the following main areas of therapy for hereditary diseases.

1. Complete or partial elimination from food of the substrate or substrate precursor of the blocked metabolic reaction. This technique is used in cases where excessive accumulation of the substrate has a toxic effect on the body. Sometimes (especially when the substrate is not vital and can be synthesized in sufficient quantities by roundabout ways), such diet therapy has a very good effect. A typical example is galactosemia. The situation is somewhat more complicated with phenylketonuria. Phenylalanine is an essential amino acid, so it cannot be completely excluded from food, but it is necessary to individually select the minimum required dose of phenylalanine for the patient.

2. Replenishment of cofactors from the outside in order to increase the activity of the enzyme. Most often it is a question of vitamins. Their additional administration to a patient with a hereditary pathology gives a positive effect when the mutation impairs the ability of the enzyme to combine with the activated form of the vitamin in vitamin-sensitive hereditary vitamin deficiencies.

3. Neutralization and elimination of excretion of toxic products that accumulate in case of blocking their further metabolism. These products include, for example, copper in Wilson-Konovalov's disease. Penicillamine is administered to the patient to neutralize copper.

4. Artificial introduction into the patient's body of a product of a reaction blocked in him. For example, taking cytidilic acid for orotoaciduria (a disease in which the synthesis of pyrimidines suffers) eliminates the phenomena of megaloblastic anemia.

5. Impact on "spoiled" molecules. This method is used to treat sickle cell anemia and is aimed at reducing the likelihood of formation of hemoglobin 3 crystals. Acetylsalicylic acid increases the acetylation of HbS and thus reduces its hydrophobicity, which causes the aggregation of this protein.

6. Introduction of a missing hormone or enzyme. Initially, this method was developed and is still successfully used to treat diabetes mellitus by introducing insulin into the patient's body. Later, other hormones began to be used for similar purposes. The use of enzyme replacement therapy, however, despite all its attractiveness, encounters a number of difficulties: 1) not in all cases there is a way to deliver the enzyme to the desired cells and at the same time protect it from degradation; 2) if the synthesis of one's own enzyme is completely suppressed, the exogenous enzyme is inactivated by the patient's immune system during long-term administration; 3) Obtaining and purifying enough enzymes is often a challenge in itself.

7. Blocking of the pathological activity of enzymes with the help of specific inhibitors or competitive inhibition by analogs of substrates of this enzyme. This method of treatment is used for excessive activation of blood coagulation systems, fibrinolysis, as well as for the release of lysosomal enzymes from destroyed cells.

Comparison of the molecular mechanisms affected in hereditary diseases with the therapeutic methods used for their treatment shows that not all the main symptoms of genetically determined human diseases can currently be eliminated. It is hoped that further study of the molecular processes underlying hereditary diseases will lead to a significant expansion of the arsenal of treatment methods in the future.

Despite the success of the symptomatic and pathogenetic treatment of hereditary diseases, the question of the possibility of their etiological treatment is not removed. And the greater the progress of theoretical biology, the more often the question of radical, i.e., etiological, treatment of hereditary diseases will be raised.

The etiological treatment of any hereditary diseases is the most optimal, since it eliminates the root cause of the disease and completely cures it. However, the elimination of the cause of a hereditary disease means such a serious "maneuvering" with genetic information in a living human body, such as "turning on" a normal gene (or its infusion), "turning off" a mutant gene, reverse mutation of a pathological allele. These tasks are difficult enough even to manipulate prokaryotes. In addition, in order to conduct an etiological treatment of any hereditary disease, it is necessary to change the DNA structure not in one cell, but in all functioning cells (and only functioning ones!). First of all, for this you need to know what change in DNA occurred during the mutation, i.e. hereditary disease must be written in chemical formulas. The complexities of this task are obvious, although methods for solving them are already available at the present time.

The principle scheme for the etiological treatment of hereditary diseases is, as it were, drawn up. For example, in hereditary diseases accompanied by a lack of enzyme activity (albinism, phenylketonuria), it is necessary to synthesize this gene and introduce it into the cells of a functioning organ. The choice of ways to synthesize a gene and deliver it to the appropriate cells is wide, and they will be replenished with the progress of medicine and biology. At the same time, it is necessary to note the importance of observing great caution in the application of genetic engineering methods (precisely in application, and not in development?) for the treatment of hereditary diseases, even if decisive breakthroughs are made in the synthesis of the corresponding genes and methods for their delivery to target cells. Human genetics does not yet have sufficient information about all the features of the functioning of the human genetic apparatus. It is still unknown how it will work after the introduction of additional genetic information. There are also other unresolved issues that do not allow us to assume "the rapid application of methods for the etiological treatment of hereditary diseases.

Prevention hereditary pathology as a whole, undoubtedly, is the most important section of modern medicine and healthcare organization. This is not just about preventing, as a rule, a serious illness in a particular individual, but also in all his subsequent generations. It is precisely because of this peculiarity of hereditary pathology, which persists from generation to generation, in the past that methods of prevention have been proposed more than once, based on eugenic approaches, in some cases more humane, in others less. Only the progress of medical genetics has fundamentally changed approaches to the prevention of hereditary pathology; a path has been passed from proposals for the sterilization of spouses or categorical recommendations for abstinence from childbearing to prenatal diagnosis, preventive treatment (treatment of healthy carriers of pathological genes that prevent the development of the disease) and an individually adaptive environment for carriers of pathological genes.

Hereditary metabolic diseases.

One of the manifestations of an unprecedented breakthrough in the accumulation of medical genetic information in the second half of the 20th century. was the discovery of a large number of new hereditary metabolic diseases (NBO) at an approximate rate of 100 new units in 10 years. The speed of their discovery, pronounced genetic heterogeneity, clinical polymorphism, low frequency of most of them make it extremely difficult for clinicians to use this information in their diagnostic practice, the clinical manifestations of NBO are so diverse that there is no such medical specialization that would not deal with its specific spectrum of NBO. Meanwhile, in domestic medicine, there is currently no modern guidance on this vast class of diseases; NBOs are not only diseases (mostly very severe) that require the solution of the entire complex of medical problems - diagnosis, treatment, and prevention. They are also unique biological models of natural metabolic errors, which are an invaluable tool for understanding the complex human metabolism in the normal. It is on these models that the role (both physiological and pathological) of a huge number of metabolites has been elucidated in recent decades, multiple connections between metabolic pathways have been established, and many metabolic pathways have been deciphered or refined.

According to modern concepts of medical genetics, hereditary diseases of human metabolism (synonymous with "molecular diseases") include an extensive class of monogenically inherited diseases caused by mutations of structural genes, under the control of which the synthesis of proteins is carried out, performing various functions: structural, transport, enzymatic catalysis, immune protection. Based on the fact that by 1988 about 4,500 monogenic human diseases were known (McKusick's catalog), and the primary biochemical defect for the first NBO (methemoglobinemia) was deciphered only in 1946 and in 1952 for the second (insufficiency of glucose-6-phosphatase in Gierke's disease) it is clear that NBO research is a rapidly developing branch of modern medical genetics. At the organismal level of NBO studies, the object of study is the clinical and biochemical phenotype of the patient, at the cellular level - mutant proteins, at the molecular level - mutant genes.

Studies of evolution and polymorphism at the molecular level over the past 20 years have shown that mutations can accumulate in populations if their selective deficiencies are small compared to the mutation rate.

The following factors influence the frequency and range of mutant alleles for each gene in populations: mutation frequency, natural selection, gene drift, and migrations. According to the first of these factors, interpopulation differences were not revealed and it is difficult to assume their existence. As for the other three factors, their influence on the gene pool of different populations is extremely uneven. The existence of geographical, linguistic, tribal, national and other barriers contributed to the subdivision of the world's population and the formation of regional characteristics of the burden of hereditary pathology, which affected the frequency and spectrum of NBO. For those NBOs. whose prevalence is estimated using fairly reliable methods, it is shown that NBOs are characterized by a pronounced unevenness of their ethnic distribution, which manifests itself both at the gene and allelic levels. It should be emphasized that at present the prevalence of most NBOs is either not estimated or estimated. This is due to a number of reasons: NBO properties. complicating their clinical diagnosis, the absence or high cost of methodological approaches and organizational difficulties. A number of organizational and methodological approaches to assessing the prevalence of NBO have been developed, which can be divided into indirect and direct.

Accurate estimates of the prevalence of NBO (direct) were obtained using mass screening, mass screening of newborns made it possible to accurately determine the incidence of phenylketonuria, adrenogenital syndrome (21-hydroxylase deficiency), galactosemia. a number of aminoacidopathy, etc. in a large number of regions of the world, predominantly with a Caucasoid population (the exception is Japan). Another approach to assessing the prevalence of NBOs is prospective screening programs (a type of mass screening) for the identification by biochemical methods of heterozygous carriers of some non-curable lethal or sublethal NBOs. widespread in a number of populations. Thus, the frequency of Tay-Sachs disease in Ashkenazi Jews in many countries of the world and a number of hemoglobinopathies in the countries of the Mediterranean region and natives of them in England and the USA was estimated. In a number of countries, neonatal capillary blood samples obtained for mass screening have been used to estimate the incidence of NBOs for which mass screening has not been established. Comparison of frequencies between populations, between regions of the same population, and between populations of the same race revealed a large difference in the frequency distribution of mutant genes. The peculiarity of genetic-automatic processes and the peculiarities of the historical development of individual populations, apparently, explain this interesting phenomenon. In the literature, attempts have been made to explain the decreasing gradient in the frequency of phenylketonuria in the countries of the North. Europe - from Ireland to Finland - the Celtic origin of the mutant allele and associate its distribution with the Viking raids.

Lethal Genes

There are cases when one gene can affect several traits, including viability. In humans and other mammals, a certain recessive gene causes internal lung adhesions to form, resulting in death at birth. Another example is a gene that affects the formation of cartilage and causes birth defects that lead to the death of the fetus or newborn.

In chickens homozygous for the allele that causes "curly" feathers, incomplete feather development entails several phenotypic effects. In such chickens, thermal insulation is insufficient, and they suffer from cooling. To compensate for the loss of heat, they have a number of structural and physiological adaptations, but these adaptations are of little effect and mortality is high among such chickens.

Impact lethal gene clearly seen in the example of the inheritance of coat color in mice. In wild mice, the coat is usually gray, of the agouti type; but some mice have yellow fur. When crossing between yellow mice, both yellow mice and agouti are obtained in the offspring in a ratio of 2: 1. The only possible explanation for these results is that yellow coat color is dominant over agouti and that all yellow mice are heterozygous. Atypical Mendelian attitude explained by death homozygous yellow mice before birth. At autopsy of pregnant yellow mice crossed with yellow mice, dead yellow mice were found in their wombs. If yellow mice and agouti were crossed, then there were no dead yellow mice in the wombs of pregnant females, since with such a crossing there cannot be offspring homozygous for the yellow wool gene .

Medical genetic counseling.

The most common and effective approach to the prevention of hereditary diseases is genetic counseling. From the point of view of healthcare organization, medical genetic counseling is one of the types of specialized medical care. The essence of counseling is as follows: 1) determining the prognosis for the birth of a child with a hereditary disease; 2) explaining the likelihood of this event to the consultants; 3) assistance to the family in making a decision.

With a high probability of the birth of a sick child, two recommendations can be correct from a preventive point of view: either abstinence from childbearing, or prenatal diagnosis, if it is possible with this nosological form.

The first cabinet for medical genetic counseling was organized in 1941 by J. Neil at the University of Michigan (USA). Furthermore, back in the late 50s, the largest Soviet geneticist and neuropathologist S. K. Davidenkov organized a medical genetic consultation at the Institute of Neuro-Psychiatric Prevention in Moscow. Currently, there are about a thousand genetic consultations all over the world, in Russia there are 80 of them.

The main reason that makes people turn to a geneticist is the desire to know the prognosis of the health of future offspring regarding hereditary pathology. As a rule, families who have a child with a hereditary or congenital disease (retrospective consultation) or its appearance is expected (prospective consultation) due to the presence of hereditary diseases in relatives, consanguineous marriage, age of parents (over 35-40 years old), exposure and for other reasons.

The effectiveness of the consultation as a medical opinion depends mainly on three factors: the accuracy of the diagnosis, the accuracy of the calculation of the genetic risk, and the level of understanding of the genetic conclusion by the counselors. Essentially, these are three stages of counseling.

First stage counseling always begins with clarifying the diagnosis of a hereditary disease. An accurate diagnosis is a prerequisite for any consultation. It depends on the thoroughness of clinical and genealogical research, on knowledge of the latest data on hereditary pathology, on special studies (cytogenic, biochemical, electrophysiological, gene linkage, etc.).

genealogical research is one of the main methods in the practice of medical genetic counseling. All studies must be supported by documentation. Information is obtained from at least three generations of relatives in ascending and lateral lines, and data must be obtained on all family members, including those who died early.

In the course of genealogical research, it may be necessary to refer the object or its relatives for additional clinical examination in order to clarify the diagnosis.

The need for constant familiarization with new literature on hereditary pathology and genetics is dictated by diagnostic needs (several hundred new genetic variations, including anomalies, are discovered annually) and preventive ones in order to select the most modern methods of prenatal diagnosis or treatment.

Cytogenetic study applied in at least half of the consulted cases. This is due to the assessment of the prognosis of offspring with an established diagnosis of a chromosomal disease and to clarify the diagnosis in unclear cases with congenital malformations.

Biochemical, immunological and other clinical methods are not specific to genetic counseling, but are used as widely as in the diagnosis of non-hereditary diseases.

Second phase counseling - determining the prognosis of offspring. Genetic risk is determined in two ways: 1) by theoretical calculations based on genetic patterns using methods of genetic analysis and variation statistics; 2) using empirical data for multifactorial and chromosomal diseases, as well as for diseases with an unclear mechanism of genetic determination. In some cases, both principles are combined, i.e. theoretical corrections are made to the empirical data. The essence of genetic prognosis is to assess the likelihood of a hereditary pathology in future or already born children. Consulting on the prognosis of offspring, as mentioned above, is of two types: prospective and retrospective.

Prospective Counseling - this is the most effective type of prevention of hereditary diseases, when the risk of having a sick child is determined even before the onset of pregnancy or in its early stages. Most often, such consultations are held in the following cases: in the presence of consanguinity of the spouses; when cases of hereditary pathology have occurred along the line of a husband or wife; when one of the spouses is exposed to harmful environmental factors shortly before the onset of pregnancy or in its first weeks (therapeutic or diagnostic exposure, severe infections, etc.)

retrospective counseling - this is counseling after the birth of a sick child in the family regarding the health of future children. These are the most common reasons for seeking advice.

Methodically, the prognosis of offspring in diseases with different types of inheritance differs. If for monogenic (Mendelian) diseases the theoretical foundations for assessing genetic risk are quite clearly developed, then for polygenic diseases, and even more so multifactorial ones, counseling is often based on pure empiricism, reflecting the insufficient genetic knowledge of this pathology.

In mendelian diseases, the task is mainly to laboratory identification or probabilistic assessment in counselors of a certain discrete genotype underlying the disease.

In non-Mendelian diseases, it is currently impossible to isolate specific and discrete pathological genotypes that determine the development of the disease, since many genetic and environmental factors that are nonspecific in their effects can participate in its formation, i.e., the same effect (disease) can be caused different genes and/or environmental factors. This creates numerous difficulties in the genetic analysis of non-Mendelian traits and diseases.

The third stage of counseling is final. After making a diagnosis in an object, examining relatives, solving a genetic problem to determine the genetic risk, the geneticist explains to the family in an accessible form the meaning of the genetic risk or the essence of prenatal diagnosis and helps her in making a decision.

It is generally accepted that specific genetic risk is up to 5% low, up to 10% - mildly elevated, up to 20% - medium and above 20% - high. It is possible to neglect the risk, which does not go beyond the limits of an increased mild degree, and not consider it a contraindication to further childbearing. Only a moderate genetic risk is regarded as a contraindication to conception or as an indication for the termination of an existing pregnancy if the family does not want to be at risk.

From a social point of view, the goal of genetic counseling in general is to reduce the frequency of pathological genes in human populations, and the goal of a specific consultation is to help the family decide on the possibility of childbearing. With the widespread introduction of genetic counseling, some reduction in the frequency of hereditary diseases, as well as mortality, especially among children, can be achieved. However, the reduction in the frequency of severe dominant diseases in populations as a result of medical genetic counseling will not be significant, because 80-90% of them are new mutations.

The effectiveness of medical genetic counseling depends on the extent to which the counselors understand the information they have received. It also depends on the nature of the legal laws in the country relating to termination of pregnancy, welfare of the sick, etc.

Genetic monitoring.

Pollution of the natural environment with harmful production wastes, products of incomplete combustion, pesticides and other mutagens, an increase in the background of ionizing radiation caused by testing of atomic weapons, the uncontrolled use of chemical and radioactive substances in energy, industry, and agriculture - all this leads to a significant increase in genetic disorders.

The genetic burden associated with these genetic disorders that undermine the hereditary health of the population is growing. So in the USSR since the eightieth year, 200,000 children were born with serious genetic defects and about 30,000 dead. About 25% of pregnancies do not endure for genetic reasons. Currently, 10% of the total population has a mental disorder. The number of oncological diseases is also increasing. And at the same time, in most cases, diseases are associated with environmental pollution. According to WHO, 80% of diseases are caused by the state of environmental stress. Therefore, the problems of genetics, ecology and human adaptation become especially acute.

The most expedient at the moment for solving the problems of human ecology is the use of monitoring the environment and the social and labor potential of people. The purpose of monitoring is to identify physical, chemical, biological pollution of the environment. Environmental monitoring is carried out on the basis of an assessment of the health structures of the population in various territorial-industrial complexes. At the same time, the obtained statistical data cannot be considered absolutely accurate, since they can only state the growth of diseases. The absence of clear criteria for health and effective means his ratings. Undoubtedly, environmental monitoring, as well as other methods of solving environmental problems, affect genetics in one way or another. Meanwhile, the genetic pollution of our planet is more dangerous than all others. It becomes necessary to predict changes in the growth of diseases. That's why special meaning has genetic monitoring that allows to control the mutation process in humans, to identify and prevent all the possibility of genetic danger associated with yet undiscovered mutagens.

At the moment, however, mutation research is difficult to implement.

The difficulties encountered in the study of mutations are primarily related to the problem of their detection in the human body. So, for example, the situation is with the registration of a recessive anomaly, since such a mutant gene appears in the body in a homozygous state, which takes some time to reach. The situation is much simpler with the registration of dominant gene and chromosome mutations, especially if their appearance in the phenotype is easily detectable.

Thanks to bioecological monitoring through the typification of climatic-geographical and production areas according to health structures (that is, according to the ratios between groups with different levels of health), it is possible to more effectively improve environmental conditions, as well as increase the level of public health. Although many problems remain. So, for example, indicators of birth rate, morbidity and mortality rather inertly “respond” to changes in the environment, and only the consequences of environmental trouble are revealed, which does not make it possible to promptly manage the environmental situation.

A number of necessary economic mechanisms have not yet been developed to stimulate environmental protection measures. Although genetic monitoring is a complex matter, it is simply necessary to solve human environmental problems, as well as reduce the growth of diseases, including hereditary ones.

Conclusion.

Genetics is a relatively young science. But it faces very serious problems for a person. So genetics is very important for solving many medical issues, primarily related to various hereditary diseases of the nervous system (epilepsy, schizophrenia), endocrine system (cretinism), blood (hemophilia, some anemia), as well as the existence of a number of severe defects in the human structure: short fingers, muscle atrophy and others. With the help of the latest cytological methods, cytogenetic in particular, extensive studies of the genetic causes of various diseases are being carried out, thanks to which there is a new branch of medicine - medical cytogenetics.

Sections of genetics related to the study of the effect of mutagens on cells (such as radiation genetics) are directly related to preventive medicine.

Genetics began to play a special role in the pharmaceutical industry with the development of genetics of microorganisms and genetic engineering. Undoubtedly, much remains unexplored, for example, the process of mutations or the causes of the appearance of malignant tumors. It is precisely its importance for solving many human problems that causes an urgent need for the further development of genetics. Moreover, each person is responsible for the hereditary well-being of his children, while his biological education is an important factor, since knowledge in the field of anomalies, physiology, genetics will warn a person from making mistakes.

References.

1. A.O. Ruvinsky "Hereditary variability of man"
2. Yu.Ya. Kerkis "Treatment and prevention of certain human hereditary diseases"
3. D.K. Belyayav "General Biology"
4. N. Green, W. Stout "Biology"
5. S. Kotov "Medical Genetics"
6. M.D. Frank-Kamenetsky "The most important molecule"

BELARUSIANII STATE UNIVERSITY

CHAIR OF PHILOSOPHY AND METHODOLOGY OF SCIENCE

ABSTRACT ON PHILOSOPHY AND METHODOLOGY OF SCIENCE

Subject No. 179

« Worldview and socio-ethical problems of human genetics »

PhD students

Department of Biophysics

physical faculty

Rooster M.G.

INTRODUCTION

The 20th century was the century of the greatest discoveries in all areas of natural science, the century of the scientific and technological revolution, which changed both the appearance of the Earth and the appearance of its inhabitants. Science and, in particular, biology and medicine have received colossal opportunities to interfere in the existence of biological objects and humans, to make radical changes in the natural conditions surrounding them. This made it possible, along with hopes, to express concerns related to the limits of permissible manipulation of biological processes, especially those related to people. Today, bioethics can be considered as a form of such preventive knowledge.

Perhaps one of the main branches of knowledge that will shape our world in the coming centuries is genetics. Genetics is one of the main, most fascinating and at the same time complex disciplines of modern natural science. The place of genetics among the biological sciences and the special interest in it are determined by the fact that it studies the basic properties of organisms and thus provides mankind with incredible advantages. Recent advances in genetics have opened up broad prospects for the development of biotechnologies, thereby giving rise to many controversies and contradictions of an ideological and socio-ethical nature.

According to Kant, man is "a being endowed with feelings and reason." And thanks to this, taken also as a person, he "is a being capable of incurring obligations." All obligations of a person in relation to himself, and thus in relation to the environment, since otherwise the existence of a person as a person is impossible, are ethical obligations. Having once developed codes and commandments, humanity saved itself, but has its behavior always been and is it reasonable? What danger can threaten him today? Does man have the right to change what is created by nature? Does he have the right to correct her mistakes and, if so, where is the line that cannot be crossed? Will scientific knowledge turn into a catastrophe for all mankind, as happened when the energy of the atom was discovered, which destroyed Hiroshima, Nagasaki and Chernobyl? There are no unambiguous answers to these questions.

Historical progress makes it possible to humanize social ties and optimize the interaction between society and nature, man and the environment, and consciously regulate the relationship between the social and the biological.

Biological and social, for all their interdependence, are in many ways different spheres of being. There are patterns in each of these areas. It is necessary to find a real, concrete way of interaction between the biological and the social, in which both would not be identified with each other and would not be separated from each other, that is, to reveal the specificity of each of these spheres of being and, at the same time, the continuity, the relationship between them.

The interaction of the biological and the social is very clearly manifested in the mental activity of a person, in the field of consciousness. The theory, sociology and ethics of biological knowledge penetrate into the very "body" of science. They become a necessary attribute of biological thinking, determine the progress of biological knowledge and the whole complex of sciences that make it possible to study a person.

Therefore, in the present work, an attempt was made not only to identify the problems of human genetics themselves, but also, if possible, to reflect different points of view on them.

1 A BRIEF HISTORY OF GENETICS

Man formed in the course of evolution modern type already had an extremely complex brain, as it were, in anticipation of future tasks that would confront him many millennia later, when it would be necessary to use the laws of quantum mechanics to master the energy of the atom and learn the laws of celestial mechanics in order to land on a neighboring celestial body; or develop biotechnological methods for cloning organisms in case of hiding from the possible future danger of depopulation with a theoretically acceptable loss of the ability to reproduce sexually. In this series of man's temptations to control the surrounding world, his claim to a special kind of creativity, the creation of living forms, stands out. It began by historical standards not so long ago.

The origins of genetics, like any science, should be sought in practice. Genetics arose in connection with the breeding of domestic animals and the cultivation of plants, as well as with the development of medicine. Since man began to use the crossing of animals and plants, he was faced with the fact that the properties and characteristics of the offspring depend on the properties of the parent individuals chosen for crossing. By selecting and crossing the best descendants, from generation to generation, a person created related groups - lines, and then breeds and varieties with hereditary properties characteristic of them.

Although these observations and comparisons could not yet become the basis for the formation of science, the rapid development of animal husbandry and breeding, as well as crop and seed production in the second half of the 19th century, gave rise to an increased interest in the analysis of the phenomenon of heredity.

The development of the science of heredity and variability was especially strongly promoted by Charles Darwin's theory of the origin of species, which introduced the historical method of studying the evolution of organisms into biology. Darwin himself put a lot of effort into the study of heredity and variability. He collected a huge amount of facts, based on them made a number of correct ones, but he failed to establish the laws of heredity. His contemporaries, the so-called hybridizers, who crossed various forms and looked for the degree of similarity and difference between parents and offspring, also failed to establish general patterns of inheritance.

The first truly scientific step forward in the study of heredity was made by an Austrian monk Gregor Mendel, who in 1866 published an article that laid the foundations of modern genetics. Mendel showed that hereditary inclinations do not mix, but are transmitted from parents to descendants in the form of discrete (isolated) units. These units, represented in individuals by pairs (alleles), remain discrete and are passed on to subsequent generations in male and female gametes, each of which contains one unit from each pair. Later Danish botanist Johansen named these units "genes".

The official date of birth of geneticists is 1900, when the data of G. de Vries, K. Correns and K. Chermak were published, which actually rediscovered the patterns of inheritance of traits established by G. Mendel. The first decades of the 20th century turned out to be extremely fruitful in the development of the main provisions and directions of genetics. The concept of mutations, populations and pure lines of organisms was formulated, the chromosome theory of heredity was discovered, the law of homological series was discovered, data were obtained on the occurrence of hereditary changes under the action of X-rays, and the development of the foundations of the genetics of populations of organisms was begun. The first gene to be localized was the gene for color blindness, mapped on the sex chromosome in 1911. In 1953, an article by biologists James Watson and Francis Crick was published in an international scientific journal on the structure of deoxyribonucleic acid (DNA), one of the substances constantly present in chromosomes. Research on the structure of the cell, the functions of proteins, the structure of nucleic acids has put researchers in front of the temptation to construct a gene artificially. This was undertaken by a group of biochemists from the Massachusetts Institute of Technology, led by Nobel Prize winner Dr. Gan Gabind Korana. By 1970, they had succeeded in constructing a DNA segment of 85 base pairs, and in 1976 there was a report that for the first time an artificial gene was working. As early as 1988, gene therapy was used for the first time.

At the end of the 20th century, genetics came close to solving one of the fundamental questions of biological science - the question of the complete decoding of hereditary information about a person.

220 scientists from different countries, including five Soviet biologists, took part in the implementation of a grandiose project to decipher the DNA genetic code, called HUGO (Human Genome Organization).

The idea of ​​organizing such a program was first put forward in 1986. Then the idea seemed unacceptable: the human genome, that is, the totality of all its genes, contains about three billion nucleotides, and in the late 80s, the cost of determining one nucleotide was about 5 US dollars. In addition, the technologies of the 80s allowed one person to determine no more than 100,000 nucleotides per year. Nevertheless, already in 1988, the US Congress approved the creation of an American research project in this area, the head of the program, J. Watson, defined its prospects as follows: "I see an exceptional opportunity for improving humanity in the near future." By 1990, the number of identified genes reached 5000, of which 1825 were mapped, 460 were sequenced. It was possible to localize the genes associated with the most severe hereditary diseases, such as Alzheimer's disease, Duchenne muscular dystrophy, cystic fibrosis. One of the important achievements was the discovery of the so-called polymerase chain reaction, which makes it possible to obtain a DNA volume sufficient for genetic analysis from microscopic amounts of DNA in a few hours. Devices have been created that are capable of sequencing (from Latin sequi - to follow) up to 35 million nucleotide sequences per year. Thus, the human genome research project is of great importance for studying the molecular basis of hereditary diseases, their diagnosis, prevention and treatment.

Today, scientists can cut a DNA molecule in the desired place in a test tube, isolate and purify its individual fragments, synthesize them from two deoxyribonucleotides, and can sew such fragments together. The result of such manipulations are "hybrid", or recombinant DNA molecules, which previously did not exist in nature. The opening prospects for the synthesis of living matter attract great attention of geneticists, biochemists, physicists and other specialists.

Modern genetics has provided new opportunities for studying the activity of an organism: with the help of induced mutations, it is possible to turn off and turn on almost any physiological processes, interrupt the biosynthesis of proteins in the cell, change morphogenesis, stop development at a certain stage, allows you to more deeply explore population and evolutionary processes, study hereditary diseases. , the problem of cancer and much more. In recent years, the rapid development of molecular biological approaches and methods has allowed geneticists not only to decipher the genomes of many organisms, but also to design living beings with desired properties. Thus, genetics opens up ways to model biological processes.

2 DEFINITION AND MAIN OBJECTIVES OF GENETICS

Genetics is the science of the laws of heredity and variability, as well as the biological mechanisms that provide them. Genetic research pursues goals of two kinds: knowledge of the laws of heredity and variability, and the search for ways to use these laws in practice. Therefore, the main areas of research by geneticists are the study of nucleic acid molecules, the keepers of hereditary information, the study of the mechanisms and patterns of transmission of genetic information from generation to generation, the study of the mechanisms for the implementation of genetic information into specific traits and properties of organisms, the elucidation of the causes and mechanisms of changes in genetic information in different developmental stages of organisms.

Genetics as a science solves the following main tasks:

1. studies the ways of storing genetic information in different organisms and its material carriers;

2. analyzes the ways of transferring hereditary information from one generation to another;

3. reveals the mechanisms and patterns of implementation of genetic information in the process of individual development and the influence of environmental conditions on them;

4. studies the patterns and mechanisms of variability, as well as its role in adaptive reactions and in the evolutionary process;

5. looks for ways to correct damaged genetic information.

According to many modern biologists, genetics has become the core of all biological science. It combines embryology and developmental biology, morphology and physiology into a single whole. Based on genetic research, new fields of knowledge (molecular biology, molecular genetics), related biotechnologies (such as genetic engineering) and methods (such as polymerase chain reaction), making it possible to isolate and synthesize nucleotide sequences, integrate them into the genome, and obtain hybrid DNA with properties that did not exist in nature. Many drugs have been obtained, without which medicine is already unthinkable. The principles of breeding transgenic plants and animals with characteristics of different species have been developed.

3 APPLICATIONS OF GENETICS

The information accumulated by modern experimental genetics makes it possible to state that on the basis and as a result of the self-development of biologically organized matter (and this, in fact, is the essence of the process of evolution of life), informational genetic systems have arisen. The very concept of "genetic information" as a term was adopted in 1944 after the publication of the book by E. Schrödinger "What is life? From a physics point of view? Genetic information is recorded on bioorganic macromolecules - DNA and RNA, it originated on the lifeless Earth several billion years ago, gave rise to living beings, ensured their variability and evolution, populated the planet with them and formed its biosphere. Genetic information dictates how organisms survive, grow and reproduce. genetic engineering interferes with this process. The very phenomenon of genetic engineering, which arose at the will of man, is described by various terms: "genetic manipulation", "genetic modification", "recombinant DNA technology" and even "modern biotechnology". The fundamental feature of genetic engineering is the ability to create DNA structures that are never formed in nature. Genetic engineering has overcome the barrier that exists in the living world, where genetic exchange is carried out only within one species or closely related species of organisms. It allows you to transfer genes from one living organism to any other. This new technique has opened up limitless prospects for the creation of microorganisms, plants and animals with new useful properties.

Genetic engineering uses the most important discoveries of molecular genetics to develop new research methods, obtain new genetic data, and also in practical activities, in particular in medicine. For example, earlier vaccines were made only from killed or weakened bacteria or viruses capable of inducing immunity in humans through the formation of specific antibody proteins. Such vaccines lead to the development of strong immunity, but they also have disadvantages. For example, one cannot be sure that the virus is sufficiently inactivated. There are cases when the vaccine strain of the polio virus due to mutations turned into a dangerous, close to the usual virulent strain.

It is safer to vaccinate with pure proteins of the shell of viruses - they cannot multiply, tk. they do not have nucleic acids, but they cause the production of antibodies. They can be obtained by genetic engineering.

If by the beginning of the 1980s the term "genetic engineering" was hardly known outside of research laboratories, today public opinion has become polarized: there are both supporters of genetic manipulations and opponents who call for prudence in choosing these means that can change a person's life from far greater consequences than previous scientific and technological breakthroughs.

3.1 Gene therapy

Gene therapy is a complex of therapeutic measures based on the introduction of transgenes into a diseased organism. Functioning in cells, they can have a therapeutic effect by: 1) compensating for a congenital or acquired genetic defect, 2) reducing the synthesis of a "harmful" protein in the body, and 3) suppressing the function of a "sick" gene. The "devices" or vectors that introduce the transgene into the cells of the body are non-dangerous viruses, into which the desired transgene is inserted in advance. Infecting and developing in the body, the vector virus activates the "healing" transgene.

The emerging successes in the etiological treatment of hereditary and congenital diseases with the help of gene therapy have led to the emergence of a new direction, a kind of "molecular prosthetics". This area is steadily gaining momentum not only in laboratories, but also in clinics. Somatic gene therapy involves the introduction of a "corrected" gene variant simultaneously into a large number of cells of an adult organism, while the changes are not transmitted to offspring. Embryonic gene therapy is associated with the manipulation of the genetic code of the embryo, which promises to enable the transmission of an already corrected gene variant to subsequent generations. Genetic prenatal diagnostics is widely used for a number of monogenetic diseases, for example, phenylketonuria, hemophilia, sickle cell anemia, etc.

3.2 stem cells

Stem cells are living cells that can divide indefinitely and transform into any of the body's tissues. They can be obtained from several kinds of sources. The most promising source of stem cells is the blastocyst - an embryo on early stage development (5-6 days after fertilization). The blastocyst consists of an outer layer of cells that will become the placenta, and an inner cell mass that will divide and specialize to form all the tissues of the body. The inner cell mass is isolated in the laboratory and grown in a nutrient medium into a colony of "pluripotent" stem cells. With the help of genetic manipulations, this colony can be purposefully turned into any desired tissue. Human embryonic stem cells were first isolated by American scientist James Thompson of the University of Wisconsin in 1999. In addition to early embryos, there are a number of other sources of stem cells. One of them is the tissues of an adult organism. Stem cells are found in the bone marrow, brain, skin and blood of the adult body, and it seems likely that they will be found in other tissues in the near future. There are also significant prospects for another method of obtaining stem cells, which is called "somatic cell nuclear transfer". Its essence lies in the fact that the nucleus of the egg is replaced by the nucleus of a somatic (i.e., any non-sex) cell extracted from an adult organism. The resulting cell is theoretically capable of developing into a full-fledged animal or human organism. This procedure has another, more common name - cloning. Abortive fetuses and miscarriages are another source of pluripotent stem cells.

Currently, stem cell research is one of the most relevant areas of biomedicine and, according to scientists, can be of revolutionary practical importance in medicine.

First, they will increase the efficiency of studies of the early stages of embryonic development at the molecular biological level. The study of stem cells physically located outside the female womb will help to more clearly trace and better understand the anomalies that arise at this stage.

Second, stem cells open up new and safer possibilities for drug testing. It is known that biomedicine uses human material (embryo, embryo, tissues of an adult, etc.) for research and therapeutic purposes either as an object or as a "raw material" for experiment or therapy. Animal testing cannot guarantee the safety of individual biomedical technologies for humans. It is not surprising that the inevitable "objectification" of man in research process on the one hand, and the presence of risks to the health of the patient, on the other hand, give rise to a number of problematic ethical issues that are becoming increasingly prominent in society in the context of protecting human rights and dignity. But these problems can be solved by using artificially grown cells of the heart, skin, liver, kidneys, etc. to test drugs for toxicity even before clinical trials in adults.

However, the main area of ​​application of stem cells is biomedicine. Stem cells, if they can be manipulated, will expand the very definition of medicine, marking the transition from the prevention or control of the symptoms of diseases (which is the traditional task of medical practice) to "regenerative" medicine, i.e. restoration of lost vital functions of organs.

The results of the work of many geneticists have already been introduced into the field of transplantation technology. It has been shown that the use of fetal (germ) and embryonic cells with weakly expressed antigens reduces the level of post-transplantation complications by an order of magnitude. In addition, they are endowed with a powerful reproductive potential, as they contain a unique set of growth factors that stimulate the regeneration of donor tissue.

The use of adult stem cells, as a rule, does not raise any serious ethical objections, but is the least effective. It is believed that the most promising sources of "raw materials" for research are early embryos, which is the most problematic from an ethical point of view.

3.4 Cloning

Cloning from a scientific point of view is the formation of identical descendants (clones) through asexual reproduction. The result of cloning is a population of cells or organisms with the same set of genes (genotype). If we talk about a human clone, then this is simply an identical twin of another person, delayed in time. Human clones will be ordinary human beings. They will be carried by an ordinary woman for 9 months, they will be born and will be brought up in the family, like any other child. Just like identical twins, the clone and the DNA donor will have different fingerprints. The clone will not inherit any of the original individual's memories. Thanks to all these differences, a clone is not a photocopy or double of a person, but simply a younger identical twin.

The issues of artificial reproduction, and first of all of man, have worried many minds since the time of Aristotle (384 - 322 BC) or the alchemists Paracelsus (1493 - 1541) and Van - Helminth (1577 - 1644). True, their experiments from the point of view of modern natural science did not have even the rudiments of scientific justification. So, for example, Paracelsus proved that it is possible to make a person in a flask. He even came up with a name for this creature - “homunculus”, in Latin “homo” is a person. Here is his recipe: “Take human fluid and leave it to rot first in a pumpkin, then in a horse's stomach for forty days, until it starts to live, move and swarm, which is easy to notice. What happens is not at all like a person, it is transparent and without a body. But if then every day, secretly and carefully, you feed it with human blood and keep it for forty weeks at a constant and even temperature of a horse's stomach, then a real living child will occur, having all members, like a child born from a woman, only very vertically challenged". Like other "scientists" of that time, Paracelsus claimed that he reproduced all this in his laboratory, but no one except him himself saw this "man".

The first experiments in this direction, which can be regarded as an undoubted achievement of science, lead to the middle of the 20th century. So in 1943, the egg was successfully fertilized, and in 1978 the first test-tube baby was born. In 1981, Professor L. Shetles of Columbia University in New York receives three cloned human embryos.

The world sensation was the message about the birth of a cloned child - a girl in a family of young Americans on December 26, 2002. She was named symbolically - Eve. This news gave impetus to endless disputes about how this “technology” should be treated - as another outstanding victory of science or as an unacceptable human intrusion into a sphere hitherto subject only to the Creator himself?

The possibility of cloning has potentially incredible benefits for humanity.

Cloning of organs and tissues is the number one task in the field of transplantology, traumatology and other areas of medicine and biology. The Eurotransplant organization is headquartered in Holland and unites doctors from many countries. Its database contains information on 12,000 patients in need of organ transplants. Most of them are wealthy people, because. medical services for organ transplants are expensive. A kidney transplant costs a patient $40,000, a heart transplant costs about $100,000, and a liver transplant costs almost half a million.

Organ transplantation from donors is a very complex operation, followed by an equally difficult period of transplant engraftment. Very often the transplant is rejected and the patient dies. Scientists hope that these problems can be solved with the help of cloning. When transplanting a cloned organ, it will be possible to avoid a rejection reaction and possible consequences in the form of cancer that develops against the background of immunodeficiency. People who need urgent surgery will no longer have to wait for “their” organ. They will have a 100% guarantee that the transplant operation will take place on time. Cloned organs will be a lifesaver for older people who need radical help due to diseases of old age (worn out heart, diseased liver, etc.).

Cloning will help people suffering from severe genetic diseases to have children. For example, if the genes that determine any such disease are contained in the father's chromosomes, then the nucleus of her own somatic cell is transplanted into the mother's egg - and then a child will appear, devoid of dangerous genes, an exact copy of the mother. If these genes are contained in the mother's chromosomes, then the nucleus of the father's somatic cell will be transferred to her egg cell - a healthy child, a copy of the father, will appear.

The most obvious effect of cloning is to enable childless people to have children of their own. Millions of married couples around the world today suffer, being doomed to remain without descendants.

Cloning can also be used to breed animals to obtain new drugs from their tissues and organs. Such animals that produce human ("therapeutic") proteins can subsequently be used to treat humans.

Exceptional individuals are valuable in many ways, both culturally and financially. In appearance, the clone almost completely repeats the original individual. For famous supermodels and movie stars, this may be the most important quality. Identical twins have a 70% correlation in intelligence and a 50% correlation in traits. This means that if you clone an outstanding scientist, then his twin clone may actually be even smarter than the original scientist! It would probably be worth cloning great actors, athletes, prominent intellectuals and scientists, each of the Nobel laureates for the future contribution that their twins could potentially make to science, culture, sports. Richard Schickel said in his essay on Clint Eastwood: "For actors, more than anyone else, genetics is destiny." Cloning is reasonable even in the case of mere mortals. The concept of "exceptional people" is not limited to movie stars and Nobel Prize winners. We all know people whom we respect and admire and consider worthy of "living after death."

Scientists have previously shown that it is not necessary for DNA donors, whether animal or human, to be alive when cloning is performed. If the tissue sample is frozen properly, it would be possible to create a clone even long after its death. In the case of people who have already died and whose tissue has not been frozen, cloning becomes more difficult, and today's technology does not allow this.

At the present stage of the development of science, the creation of a whole organism by cloning with a predictable development process is very doubtful, and in some cases not scientific and needs serious justification. There are fundamental questions, without knowing the answers to which, it is impossible to seriously talk about cloning the human body. The level of modern ideas about the laws of shaping makes this problem unsolvable in the near future.

To date, experiments on human cloning are prohibited (or a moratorium has been imposed) in almost all developed and developing countries, in addition, there is a special resolution of the UN Security Council introducing a moratorium on any experiments on cloning humans and embryos older than a two-week development period.

3.4 Eugenics

In the mass consciousness, eugenics is perceived as an attribute of racism, a phenomenon characteristic only of the totalitarian states of the 20th century.

It is believed that eugenics as a science of racial hygiene originated in the Third Reich and that eugenics research was carried out only in Hitler's Germany. It is by no means the flourishing of these studies that is connected with Germany, but, on the contrary, their complete discrediting.

However, eugenic practice had already existed many centuries before. The basics of selection have been known to pastoral peoples since ancient times. In Sparta, frail babies were destroyed by being thrown into the abyss, as a result of which a type of invulnerable Spartan warrior arose. Plato wrote that one should not raise children with defects, or born from defective parents. The handicapped, as well as victims of their own vices, should be denied medical care, and "moral degenerates" should be executed. On the other hand, the ideal society, according to Plato, is obliged to encourage temporary unions of selected men and women so that they leave high-quality offspring. In ancient Greece, any quality that was not in the other inhabitants of this society was considered ugliness, i.e. racial features also became signs of ugliness. A great merit in the study of pathology belongs to Aristotle, who defined ugliness as a manifestation of the variability of the living, thereby refuting the mystical view of pathology. In the Middle Ages, the religious-mystical view of pathology again prevailed, and ugliness began to be considered a punishment for the sinful essence of the human race. In France, the grenadiers of the Napoleonic army were selected according to special criteria, including height. The death of most of this army elite significantly affected the gene pool of the nation. For example, the average height of the French has become lower.

The history of Russian eugenics began in the era of Peter the Great. According to Peter’s decree “On the Testimony of Fools in the Senate”, “Fools who are not fit for any science and service”, were forbidden to marry, because it was impossible to expect a “good heritage and state benefit” from them. This decree was frankly eugenic in nature and testified that Peter the Great was interested in the problems of heredity. Another action of Peter, according to eugenicists, was of the opposite, anti-eugenic character, but was also associated with Peter's desire to experiment with the phenomenon of heredity - we are talking about the famous wedding of dwarfs arranged in November 1710.

The term "eugenics" (from the Greek "eugene" - noble) was first introduced in 1883 in the book Inquiries into Human Faculty and Its Development. In 1904, Galton defined eugenics as "the science concerned with all the factors which improve the inborn qualities of a race". According to Galton, eugenics is designed to develop and theoretically justify methods of social control that "may correct or improve the racial qualities of future generations, both physical and intellectual." He came to the conclusion about the need to protect the gene pool of the chosen human race, selecting its best representatives, endowed with outstanding abilities. Galton believed that abilities are inherited, and living conditions only contribute to the development of what is inherited from ancestors. Consequently, eugenics had to solve such universal problems as the fight against hereditary diseases, the general increase in the intellectual potential of mankind, etc. The eugenic direction of research was readily supported by a number of scientific circles, and then became an academic discipline taught in many colleges and universities.

Over time, eugenic theories found wide application. The governments of some countries have implemented certain practical steps to improve human qualities.

In the United States, Germany and other countries of Western Europe, during the first half of the 20th century, many programs of scientifically based selection of married couples for the production of offspring with high genetic qualities were created. It is important to note that many of these types of programs had legislative formalization (although there were also secret actions).

In 1920, the Russian Eugenic Society was established. A periodical publication - "Russian Eugenic Journal" - begins to appear. Eugenics acquired a special status in Soviet Russia - the emphasis was placed on the formation of a new human generation, "homo sovieticus". All this gave the research of eugenicists a special political meaning. Professor V. Gorinevsky sounded the alarm: eugenics must immediately come to the aid of Soviet society, in which signs of degeneration were clearly visible. It turned out that degeneration can affect not only the bourgeois classes of exploiters, but also the proletariat. As a result of two wars, imperialist and civil, “the population of Russia not only thinned out,” wrote Gorinevsky, “it immediately became qualitatively worse, since the best elements of the whole people went to war - the stronger, the healthiest, the best workers ...” . For five years of civil unrest, the population of the country decreased by almost 13 million people - mostly they were victims of famine, various epidemics, as well as those who died in battles, from the red and white terror. The potential of the people was seriously undermined. Geneticist AS Serebrovsky in 1929 made a proposal to introduce "socialist eugenics" or anthropotechnics, the essence of which was to artificially inseminate women with the sperm of talented men. Having inseminated women with the sperm of the leaders of the revolution, one could count on the emergence of a new generation of fighters for a brighter future.

In the United States, eugenics was supposed to serve social objectives, to eradicate alcoholism, prostitution, crime, hereditary mental illness. The beginning of the practice of legislative formulation of eugenics policy in the United States can be dated back to 1907, when the first law on forced sterilization of handicapped citizens on eugenic grounds was passed in the United States in the state of Indiana. Similar laws were later passed in almost thirty states. They simultaneously prohibited interracial marriages, which “polluted” the gene pool of the nation with poor-quality genes. As a result, about 50,000 cases of forced sterilization were recorded in the United States before World War II. There was also the practice of a judicial deal - the expression by a recidivist (in a significant number of cases they were distressed emigrants caught on repeated petty theft) of “voluntary” consent to sterilization in exchange for a reduced sentence for a criminal offense. Even now, some US states provide for the possibility of replacing life imprisonment for sex offenders with voluntary castration. In this case, castration performs both a preventive and punitive role.

At the International Congress on Eugenics, held in New York in 1932, one of the scientific eugenicists said: “There is no doubt that if the sterilization law in the United States were to be more enforced, the result would be less than in a hundred years, we would have eliminated at least 90% of crime, insanity, dementia, idiocy and sexual perversion, not to mention many other forms of defectiveness and degeneration. Thus, within a century, our lunatic asylums, prisons and psychiatric clinics would have been almost cleansed of their victims of human misery and suffering.

The modern genetics professor A.P. Akifiev writes in the book “Genetics and Fates”: “... there is evidence that in the USA there is even a secret sperm bank of Nobel laureates. It is well known that many Nobel Prize winners were ardent supporters of eugenics.”

Fascist Germany revealed genetics that had a religious tinge and aimed at the destruction of the "children of darkness" represented by representatives of the lower, non-Aryan races. On July 14, 1934, the law “On the Prevention of the Birth of Hereditarily Ill Offspring” was passed, according to which persons suffering from congenital dementia, schizophrenia, epilepsy, blindness, and dumbness were subject to mandatory sterilization. To enforce this law, special "courts of hereditary health" were created, which consisted of two doctors, a judge and a chairman. According to the verdict of the court, men and women, whose bad heredity was considered established, were subjected to a violent operation that prevented the possibility of childbearing. In total from 1934 to 1937. sterilization was subjected to 197419 people. Pursuing a tough eugenics policy, the National Socialists faced a difficult situation for them, when it turned out that not only representatives of the “lower races” (Jews, Gypsies), but also purebred Aryans were carriers of hereditary diseases. Before this fact, racist eugenics was helpless. Children of Aryan origin, who inherited schizophrenia, dementia or other ailments from their parents, had to study in special schools of correctional pedagogy. If it turned out that attempts at correction did not lead to success, the child could end up in the so-called "shelters", where the handicapped child was physically destroyed. Since 1939, all doctors and obstetricians were required to report the birth of every handicapped child. The fate of such a child was determined by a special commission, but, most likely, physical destruction awaited him. The most humane way was considered depriving the child of food. Thus, the ideology of racial intolerance came into conflict with eugenic practice - a purebred Aryan child could be born with the same disease as a child in a Jewish family.

At the Nuremberg trials, cases of using experiments on radiation sterilization of prisoners were considered. After radiation castration, they were sent to "general work", then they were killed and changes in the tissues of the gonads were examined. Konrad Lorenz, as a supporter of "practical" eugenics in Nazi Germany, after the Second World War became "persona non grata" in many countries. However, a number of regional and national governments supported eugenics programs until the 1970s.

Despite the fact that eugenics is a purely scientific discipline, the eugenicists of the Third Reich adopted the non-scientific, racist part of the theory and used it as a justification for the "perfection" of any race. This pushed many scientists away from eugenic ideas, making the term itself unpopular. After eugenic research in many countries were banned.

Since the late 1980s, eugenics has again become the subject of academic and political discussions as the topic of the “danger of reviving eugenics” in connection with the launch of the international research project “Human Genome”, which will give biomedicine unprecedented opportunities for diagnosing and treating genetic pathology. Articles prohibiting eugenics programs in one way or another have entered the legislation of most industrialized countries. In 1997, the “UNESCO Universal Declaration on the Human Genome and Human Rights” (signed by all UN members except Singapore) was adopted, prohibiting eugenic activities. A similar prohibition is contained in a special annex to the Council of Europe Convention on the Protection of Human Rights and Dignity in Connection with the Use of Biology and Medicine: Convention on Human Rights and Biomedicine, adopted in the same year.

Distinguish between positive and negative eugenics. The positive ones include the actions of scientists aimed at promoting the reproduction of people who have signs valuable for society (the absence of hereditary diseases, good physical development, high intelligence, etc.). The goal of negative eugenics is to stop the reproduction of those who have hereditary defects, or those who in a given society are considered physically or mentally handicapped. The line between these types of eugenics is rather conditional. The feasibility of both directions raises a number of questions.

Eugenics research has found itself at the intersection of many social, ethnic and political issues, making it more relevant than it was 100 years ago.

3.5 Genetics in forensics

In judicial practice, cases of establishing kinship are known, when children were mixed up in the maternity hospital. Sometimes this concerned children who grew up in foreign families for more than one year.

To establish kinship, methods of biological examination are used, which is carried out when the child is 1 year old and the blood system stabilizes.

A new method has been developed - gene fingerprinting, which allows analysis at the chromosomal level. In this case, the age of the child does not matter, and the relationship is established with a 100% guarantee.

4 SOCIAL AND ETHICAL PROBLEMS OF GENETICS

In recent decades, as is known, there have been widespread discussions related to the prospects for applying genetic methods to humans. This seemingly purely scientific interest unexpectedly highlighted the broad ideological, social and ethical issues associated with it. The specificity of the ethical problems of medical genetics also lies in the fact that the subject of genetic practice is the care of the unborn child.

When it comes to the danger or safety of a genetically modified world, the most common points of view are based mainly on "general considerations and common sense". For example:

In nature, and so everything is reasonably arranged, any intervention in it will only worsen everything;

· since scientists themselves cannot predict with 100% guarantee all, especially long-term, consequences of the release of transgenic organisms into nature, it is not necessary to do this at all;

· over billions of years of evolution, Nature has tried all possible options for creating living organisms, and nothing bad has happened, why should a person succeed?

· In Nature, genes are constantly being transferred between different organisms (especially between microbes and viruses), so that transgenic organisms will not add anything fundamentally new to Nature.

Genetic engineering can, on the one hand, lead to the deliverance of mankind from many troubles, in particular from hereditary diseases, and on the other hand, as a result of experiments and manipulations with genes, lead to results that pose a threat to man and mankind. The ethical assessment of what has already been achieved is distinguished by a variety of points of view. Optimists see great promise in the field of genetic therapy and biotechnology. An optimistic attitude is more characteristic of scientists - direct participants in the work, molecular biologists, and geneticists. Another point of view is more common among lawyers and philosophers. Those who adhere to it are very concerned about the possibility of genetic changes that, once started, can “change the genetic portrait of humanity so much that, in relation to the consequences of this “revolution”, the consequences of existing wars and catastrophes may seem insignificant.” It is clear that representatives of both the first and second points of view are interested in the formation of a legislative framework that favors their interests. These positions are extremely difficult to compare, since the former is based on a pragmatic argument and a factual basis. However, the very presence of the principle of pragmatism as a philosophical basis does not make this view a priori preferable. The arguments of the second group are more related to probability than to a specific fact, but it is precisely the lack of utilitarian ethics when it comes to a person (according to Kant, a person cannot be considered as a means to achieve any, even the most good goal) that allows you to listen to it. Discussions around genetic engineering indicate that ethical values ​​can and should determine the direction of research in this, and in other areas of knowledge.

The main ethical problem of modern medical genetics is the issue of confidentiality of genetic information, the arbitrariness of genetic testing, the availability of medical genetic care, etc. Manipulation with human genetic material and cells involves taking samples of biomaterial from individuals for diagnosis or extracorporeal changes in the interests of this person or his relatives. In this case, discrimination against individuals or groups on the basis of genetic information obtained about them may pose the greatest danger, which can harm not only the patient, but also relatives. This can lead to loss of a job, violation of a marriage contract, etc.

It is known that only a very small percentage of hereditary diseases can be successfully cured. Medicine is mainly limited to prevention and diagnostic methods. Then another question arises. If the information concerns the likelihood of a severe mental or somatic illness, is the geneticist obliged to provide complete information to relatives in order to avoid possible misfortune? And will a man want to know his own fate if he cannot avoid it? In this case, the genetic diagnosis can be a heavy burden for the patient and his family and become the basis for their social discrimination.

In addition, the introduction of genetic material of autologous or foreign origin into the human body to correct the work of its genome or other methods of gene therapy affect the interests of both the persons directly examined or undergoing treatment, and their relatives and descendants: their health, marital status, insurance, employment, property and etc.

It is known that Mr. main dangers of gene therapy associated with the viral nature of the transgene carrier. Such a virus should not infect other people and should not infect the germ cells of the patient, so as not to pass the transgene to the offspring and make it transgenic. However, it is currently believed that gene therapy technologies, if chosen wisely, do not pose risks to patients that go beyond conventional medical procedures.

Currently, genetic engineering is technically imperfect, since it is not able to control the process of inserting a new gene. Therefore, it is not possible to predict the insertion site and the effects of the added gene. Even if the location of the gene can be determined after its insertion into the genome, the available DNA knowledge is very incomplete in order to predict the results.

The possibility of cloning caused a great stir in the field of religion, ethics, and the protection of human rights.

Almost all religious teachings insist that the birth of a person is in the “hands” higher powers that conception and birth should occur naturally. Cloning encroaches on the divine essence of human origin, which is a sin. Cloning can lead not only to the destruction of the bonds of marriage, but also to the spread of unknown diseases. Scientists are talking just about the "correction" of those genetic defects that arose thanks to God's providence.

On the ethical side, human cloning also causes great concern. Firstly, the formation of a person as a person is based not only on biological heredity, it is also determined by the family, social and cultural environment. And, therefore, there is no way to achieve full compliance of the copy with the prototype (donor).

The clone grows from an adult cell, in the genetic structure of which so-called somatic mutations have occurred over the years. In natural fertilization, the mutated genes of one parent are compensated by the normal counterparts of the other parent. When cloning, such compensation does not occur, which is fraught for the clone with the risk of diseases caused by somatic mutations: cancer, arthritis, immunodeficiencies.

The cloned organism will bear the burden of genetic mutations of the donor cell, which means its diseases, signs of aging, etc. Consequently, the ontogenesis of clones is not identical to the ontogeny of their parents: clones go through a different life path, shortened and full of diseases. The famous sheep Dolly, who was born as a result of cloning in 1997, began to age at an incredible rate. Two calendar years later, in 1999, it turned out that her biological age was six years old! The donor of the cell from which Dolly was copied was at one time just a six-year-old sheep - it turns out that the newborn quickly made up for the age data embedded in its genome. It can be argued that cloning does not bring rejuvenation, the return of youth, immortality. Thus, the cloning method cannot be considered absolutely safe for humans.

The result of cloning can be the depletion of the gene pool. At asexual reproduction the programming of the genotype determines a smaller variety of interactions of a developing organism with changing environmental conditions.

As for the methodological aspect of the problem, it is not difficult to imagine that due to the lack of perfection of the cloning technology itself, in the course of, alas, inevitable failures, hundreds of innocent children doomed to terrible pathologies will suffer. Inexorable statistics show that if someone now decides to try to reproduce an exact copy of a person, he has only one chance in three hundred possible (the rate of survival of live specimens is 0.36%, the percentage of death of developing reconstructed eggs in the fetal period of development is 62%). Consequently, when cloning a person, each "unsuccessful copy" will turn out to be physically or mentally handicapped, but at the same time, virtually all of humanity will be responsible for it as a full-fledged person.

Therefore, it is very important for human cloning to minimize the risk, which, nevertheless, to a certain extent will still remain, the risk of defective development of the reconstructed egg, the main cause of which may be incomplete reprogramming of the genome of the donor nucleus.

The question also arises: can a woman - an egg donor put forward her rights to the resulting child, in the cells of which there is not a single of her chromosomes, but her personal - mitochondrial - DNA is present? DNA molecules, hereditary material, are contained not only in the nucleus of the cell, but also in the cytoplasm, in mitochondria - organelles responsible for the energy of the cell. Unlike nuclear DNA, mitochondrial DNA passes on to the next generation only through the mother's egg. Fathers never pass on their mitochondria to their children. How this mitochondrial DNA is involved in heredity, no one can say for sure yet. But somehow it certainly participates if it is transmitted from the mother to all her children, and then from daughters to their children, etc. In other words, we all contain in our cells the mitochondrial DNA of the foremother Eve, common to all of us. If so, then all talk about the cloning of organisms is still empty dreams. Only nuclear genes are transplanted, and the mitochondrial genes in a cloned organism will be from the cell where the nuclear genes were transplanted, i.e. strangers. The child, in turn, can say that he has two genetic mothers - according to chromosomal and mitochondrial DNA. This means that it is quite possible that lawyers will eventually have to consider the issue of ownership of their DNA - after all, cells can be taken without the consent of a person. The legal side of the problem should also affect the issue of the cells of a deceased person. The question arises, who has the right to dispose of the genetic material of the deceased for its subsequent cloning? Can an individual whose cells were cloned after death be considered a father (mother)? In addition, there is a need to create a right base, on the basis of which the abuse of cloning can be avoided. For example, there is reason to believe that the predisposition to cruelty and murder is genetically predetermined. Therefore, the cloning of convicted murderers and other violent criminals must be banned.

It should be recognized that talking about human cloning is possible only theoretically. It is obvious that today the probability of the negative consequences of this procedure far outweighs its benefits, therefore, according to many scientists and philosophers, it is not advisable to carry out work on human cloning, both at present and in the near future.

Ethical issues related to stem cells differ in a number of ways. In normal clinical practice, ethical conflicts arise and are resolved, as a rule, between two participants - the patient and the doctor. In the case of using stem cells, a third party is added to this - a stem cell donor. The problem of obtaining stem cells, their cultivation and transplantation constitute an independent stream of complex ethical problems.

The central issue around which the debate on embryonic stem cells is built is the moral and legal status of the embryo. Obtaining a colony of stem cells from an early embryo means the death of this embryo, denying it the opportunity to develop into a full-fledged organism. If an embryo is a human being, a person, then it is impermissible to do anything with it that is unacceptable to do with a person (deliberately kill, mutilate, inflict pain, etc.). If an embryo at an early stage of development is only a handful of cells, then neither ethical standards nor the law can prohibit its use for a variety of socially useful purposes. If this is an intermediate form of life, then its use is in principle possible, but with certain reservations.

The topic of the status of the embryo is linked to the question of the legality of arbitrary abortion. But in the case of stem cells, the problem of the status of the embryo takes on a new dimension. This is due to the motivation of this kind of scientific research, namely the search for new, more effective ways to treat serious diseases, for which there is objectively no antidote in modern medicine. Therefore, according to many, the traditional arguments against abortion or reproductive cloning cannot be fully applied to stem cell research.

The issue of the legal and moral status of the embryo is not so much a natural science issue as a bioethical and religious one. Here two ideological attitudes collide, each of which has a deeply felt moral justification. On the one hand, this is an attitude towards reverence for human life, the starting point of which, no matter how disputed, is still fertilization. On the other hand, this is the desire to save sick people from suffering.

Although for most people the question of the use of embryonic stem cells is very complex and the choice of one or another solution is not unambiguous, various religious movements have already developed quite a definite opinion on this issue.

Roman Catholic and Orthodox Church, as well as many Protestants say that life human personality begins at the moment of fertilization of the egg. An embryo is already an individual, only at an early stage of development. In this case, the destruction of the embryo is tantamount to killing a person. With this vision, the use of a human embryo, regardless of the purpose, seems immoral.

The opposite position belongs to a wide range of liberal Protestant traditions and consists in the fact that the formation of a person is not tied to a certain moment in time, but depends on the experience of communicating with the outside world, on the ability to perceive what gives life meaning and value. The emergence of a personality is considered here precisely as a formation, as a gradual process, stretched out in time, proceeding after the birth of a person into the world. In this sense, the early embryo is not human, and there is nothing wrong with using it for noble medical purposes.

Modern Judaism is even more liberal in regard to this problem. In the Talmudic tradition, the fertilization of the ovum is not at all regarded as the beginning of the life of the human person. Human status is acquired at a later stage in the development of the embryo. In addition, outside the female womb, the embryo has no legal status at all, which means that an embryo obtained in vitro and not intended for implantation can be used in medical research without any reservations, which corresponds to another important concept for Judaism - the preservation of life and human health as a priority moral task.

According to Muslims, the embryo is endowed with a soul only on the 40th or 120th day after fertilization (depending on the specific interpretation of the Koran), which removes any restrictions and reservations, since stem cells are cultivated from a 5-6-day embryo.

The presence of colossal ideological differences in the bioethics of stem cells causes a conscious need for serious state regulation. The problem of the status of the embryo and, in particular, of stem cells is a universal human dilemma that receives one or another sound in any society. All over the world, at the national, regional and international level, there are attempts, on the one hand, to bring the issue of stem cells under the existing regulatory framework, and on the other hand, to develop a new layer of legislation and institutional framework specifically for regulating stem cell research.

Eugenics is the most prominent area of ​​application of genetics, causing the most questions. One of the most difficult issues is to determine how to select an elite whose gene pool is valuable and must be preserved and reproduced in subsequent generations. It is known that the Spartans formed a type of invincible warrior, won the Peloponnesian War against Athens, but Sparta did not know the great commanders. The uselessness of culling "harmful" genes was also shown by the experiments of the Nazis: at one time in fascist Germany, mental patients were practically destroyed, and at first fewer children with disabilities were actually born. But 40-50 years have passed, and now the percentage of mental patients in Germany is the same as it was before.

Another stumbling block is that eugenics attempts to control people's complex behavioral traits of intelligence and giftedness, which are determined by a large number of genes. The nature of their inheritance is very complex. In addition, culture, language, upbringing conditions, education and, of course, a moment of luck play an important role in the development of talent and intelligence, although one can disagree with this. All this is transmitted to the child not through genes, but through communication with loved ones and teachers. Do not forget that talent is not the presence of any special genes, but, as a rule, their unique, amazing combination that is not repeated in generations. In addition, it is known that many geniuses suffered from one disease or another, which made them "harmful material" from a eugenic point of view. N.K. Koltsov in his article "Improving the human race" noted that "epilepsy or insanity (combined) with high talent and even genius." Here we approach the long-standing and insoluble question of the relationship between norm and anomaly. Pathology and the norm are in a dialectical relationship, each pathology gives a clearer idea of ​​the norm.

At one time, scientists (mainly geneticists, anthropologists and psychiatrists) took an active part in the scientific substantiation of the need for a politically oriented program to save the genetic health of the nation. The exact number of victims of this eugenics program is difficult to ascertain. So in January 1940, the poison gas carbon dioxide was first used in psychiatric clinics for the euthanasia of patients. Many psychiatric patients fell into the statistics of natural death, because they were simply starved to death or died after deliberately contracting a serious infectious disease.

Another problem is the change in the gender structure of society, for example, in Southeast Asia, it is widely practiced to diagnose the sex of the fetus and often abort girls. Thus, the natural ratio of boys and girls is violated.

From the point of view of eugenics, the danger of "degeneration" is especially relevant for industrialized countries. The deterioration of the ecological situation on the planet (ozone holes, increased levels of radiation, environmental poisons, mutagens and carcinogens in the environment) leads to the accumulation of harmful and unnecessary changes in the genes of people - mutations. This accumulation of mutations is called the genetic load. Mutations lead to poor health, various mental disorders, and pathologies. One of the reasons for the growth of the genetic burden is the development of medicine, which allows people with significant congenital genetic anomalies or diseases to reach reproductive age. These diseases have previously been an obstacle to the transfer of defective genetic material to the next generations. Eugenic methods are aimed at stopping the genetic degeneration of the population.

Currently, eugenic principles are partly implemented in the recommendations for desired / unwanted pregnancy - so far such assessments are based on a survey and / or biotesting of only a small category of persons included in the so-called “risk group”.

Social compensation for persons who do not have a chance to give birth to their own healthy offspring are methods of artificial insemination, as well as the institution of adoption. In a number of countries, prenatal diagnostics of an embryo developed as a result of artificial insemination (with a cell number of about 10) is already available. The presence of markers of about 6,000 hereditary diseases is determined, after which the question of the advisability of implanting the embryo in the uterus is decided. This allows couples who previously did not take risks due to the high risk of hereditary diseases to have their own child. On the other hand, some experts believe that the practice of interfering with the natural diversity of genes carries certain hidden risks. However, these methods are not designed to improve the human gene pool, but to help individual couples fulfill their desire to have a child.

The first legal documents concerning the issues of human genetics were formed on the basis of the conclusions of the 1975 conference held in Asilomar, the participants of which were the largest experts in the field of molecular genetics. For the first time at this conference, the principle of classifying the degrees of danger was developed, a list of prohibited experiments was compiled, and the need for legislative regulation and supervision in relation to genetic engineering activities was indicated. The most important legal documents currently are:

"Universal Declaration on the Human Genome and Human Rights", adopted by the General Assembly of UNESCO in 1997;

“Council of Europe Convention for the Protection of the Rights and Dignity of Man with regard to Applications of Biology and Medicine: Convention on Human Rights and Biomedicine”, adopted in 1996 by the member countries of the European Council and subsequently supplemented by a protocol prohibiting human cloning;

WHO Guidelines "Proposed International Guidelines on Ethical Issues in Medical Genetics and Genetic Services", dedicated to the ethical issues of medical genetics. (1997).

WHO Declaration on Human Cloning (“Declaration sur le clonage”, Rapp. No. 756-CR/97) (1997).

The value orientation of the subject, accompanying the process of cognition, penetrating it, determines the importance for science of this or that idea, is able to determine the strategy of research in science. At the same time, incorrect estimates are fraught with serious consequences for science. The qualification of an idea as unimportant, especially before revealing whether it is true or false, is capable of misrepresenting it as false, and thereby doing great harm to the knowledge of nature. New knowledge acquired by man is a natural factor in his own evolution. Knowledge itself, scientific research is neither good nor evil. What matters is whose hands they are in.

CONCLUSION

Among the biological sciences, perhaps highest value for humanitarian problems has genetics. Its significance, first of all, is in philosophical and historical applications: where did humanity come from, what can happen to it next, what is its place in the system of nature. Its significance is also in directly practical problems: physical and mental health, susceptibility to training and education, susceptibility to the pressures of the material and socio-economic environment that shape the personality. Moreover, theoretical and practical applications do not belong to non-overlapping areas, they are interdependent.

Genetics faces very serious problems for humans. Research in this area is very important for solving many medical issues related primarily to various hereditary diseases. In our time, biomedical sciences and technologies have reached such a level that on their basis it is possible not only to describe in terms of molecular structures and processes the fine structure of individual parts of the body and their coordinated work, but also to create fundamentally new methods for diagnosing, treating and preventing many diseases. . Achievements in the field of genetics make it possible to assess the abilities and capabilities of each person, to identify the difference between populations, to assess the degree of adaptation of a particular person to a particular environmental situation. DNA sequences can be used to determine the degree of relationship between people. The method of "genetic fingerprinting" is successfully used in forensics. Similar approaches can be used in anthropology, paleontology, ethnography, and archeology.

A feature of any developing science is that each of its new steps brings with it both new, previously unknown opportunities and formidable dangers. Mastering the energy of the atom brought not only cheap electricity, but also a weapon capable of destroying all of humanity. In this regard, the achievements of genetics pose serious social and ethical problems, the main of which is the question of the advisability of interfering with the "holy" human nature.

Over time, science and society come to the socio-ethical and humanistic regulation of science as a vital necessity. In this regard, the freedom of scientific research and the social responsibility of a scientist should not exclude each other. The fate of all mankind will depend on the development of the correct worldview and socio-humanistic positions of scientists.

The progress of science and technology is inevitable, and anyone who has embarked on the path of scientific research must do everything possible and impossible so that his discoveries are not used to the detriment of humanity, so that on our planet the mind does not destroy life, life, the infinity of which is studied by genetics, one of the great sciences of the future!

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Problems, interests and development of genetics (according to publications in the journal "Knowledge is power").
Genetics is an exciting science, designed to answer the question of Man as a whole and a phenomenon that combines the biological and rational principles. The success of genetics is the filling of blank spots on the map of Man. It is not surprising, therefore, that we have a great interest in this science. How to manage diseases, correct the shortcomings of the body, find your ancestors - all these questions and many others are within the competence of genetics.
The journal "Knowledge is Power" pays quite a lot of attention to the issues of genetics. Particularly increased interest has been shown since the mid-90s. gg.
Articles of this time reveal the milestones in the development of genetics and the features of the formation of this science in our country. A certain starting point of genetics is established - 1900. This is the year when the publication of articles by de Vries, K. Correns and E. Chermak outlining the basic laws of inheritance. The studies of G. Mendel (1856 - 1866) and the patterns of inheritance discovered by him were "rediscovered" and became known to the general scientific community.
In previous decades, many eminent researchers obtained results that in one way or another formed the basis of the theory of heredity. V.Hofmeister (Germany - discovery of the mechanism of cell division. A.Weismann (Germany) - hypothesis that chromosomes contain hereditary material in the form of discrete genes. I.Chistyakov (Russia) - analysis of the mechanism of cell division. V.Ru (Germany) - discovery of the division of chromosomes into "halves" and their equal divergence into daughter cells. the life of a cell and an organism K.Bernard (France) - proof that life is impossible without chromosomes and the hereditary material contained in them O.Gertwig (Germany) - a new life arises when two nuclei of the maternal and paternal eggs merge, when two complexes are collected chromosomes into one. E. Wilson (USA) in 1896 published the book “The Cell in Development and Heredity”, in which the facts obtained by geneticists, cytologists, embryologists, evolutionists served as the basis for a holistic theory of chromosomal inheritance. After 1900, the rapid development of research begins in the field of genetics. It employs such prominent researchers as W. Batson (England), who proposed the term "genetics", F.-A. Jansens (Belgium), A. Weisman, V. Johannsen (Belgium), T. Morgan, W. Setton , Sturtevant, G. Meller, W. Bridges (all - USA), R. Goldschmidt (Germany). Genetics has evolved rapidly. In 1913, the First International Genetic Congress took place. Russia was represented by one person - Finn Federley. 1917 - the opening of the Institute of Experimental Biology, created by N.K. Koltsov. In the early twenties, student D. Romashov and N. Timofeev-Resovsky were given the task of testing the effect of X-rays on Drosophila. 1922 - N.I. Vavilov makes a report on the "Law of Homological Series" - on the parallelism in the variability of related groups of plants, that is, on the genetic proximity of these groups. 1925 - G.A. Nadson, G.S. Filippov, G. Meller - works on radiation methods of causing mutations. 1926 - S.S. Chetverikov - an article that laid the foundations of population genetics and the synthesis of genetics and the theory of evolution. 1927 - N.K. Koltsov - the idea of ​​matrix synthesis. This idea still meets the modern ideas of biologists today: “Each chromosome is based on the thinnest thread, which is a spiral row of huge organic molecules - genes. Perhaps this whole helix is ​​one gigantic length molecule. 1929 - A.S. Serebrovsky - study of the functional complexity of the gene. 1933 - T. Morgan - Nobel Prize for the experimental substantiation of the chromosome theory of heredity.
1934 - B.L. Astaurov - successful experiments on obtaining offspring from unfertilized eggs from a silkworm, one of the most interesting achievements in applied genetics of that time. 1935 - NV Timofeev-Resovsky, KG Zimmer, M. Delbrück - experimental determination of gene size.
1943 - O. Avery - the establishment of the fact that the "substance of the gene" is DNA. Beginning of the DNA era.
1944 - M. Delbrück, S. Luria, A. Hershey - pioneering research on the genetics of Escherichia coli and its phages, after which these objects became models for genetic research for many decades.
1961 - M. Nirenberg, R. Mattei - synthesis of an artificial protein chain on an artificial seed. In the works of biochemists M. Nirenberg, S. Ochoa, X. Qur'an, the decoding of the "language of life" - the code that contains information about the structure of protein molecules - was started. In the experiments of F. Crick and S. Brenner, the main properties of the genetic code (tripletity, degeneracy) were revealed.
After 1961, the study of the molecular foundations of life reaches the modern level, and this direction becomes the leading one in the science of the 20th century.

Further publications are small articles from the Science News section about practical implications and the success of geneticists: it was possible to trace the history of mutations of the X and Y chromosomes responsible for the sex of the child. At the same time, it turned out that the discrepancy between “male” and “female” occurred approximately 300 million years ago. Prior to this, in the predecessors of mammals - reptiles - sex was determined by the temperature of incubation of eggs. And only in mammals a different sex determination system appeared - during the mutation process, the SRY gene arose, which began to be located on the Y chromosome and determine the male sex, and the X chromosome deprived of it - the female one.
For the first time, a complete genetic map of one of our chromosomes has been obtained - 545 functional genes have been identified on the twenty-second chromosome by an international group of scientists. Some of them are "responsible" for the functioning of the immune system, others - for birth defects heart disease, mental retardation, certain types of cancer, including leukemia, and schizophrenia.
The sensational discovery was made by a group of geneticists from the Institute for Genetic Research in Rockville (USA). It was found out what is the minimum number of genes that can support the life of an organism. In the bacterium Mycoplasma genitalium, which has the smallest set of genes among all organisms on Earth, this number ranged from 300 to 350 genes. These results allow us to speak quite seriously about the possibility of synthesizing "life" in the laboratory.
Employees of the University of Ulster have identified a previously unknown gene that affects the radiation resistance of living tissue. Activation of this gene increases the ability of cells to self-repair after exposure to radiation, while its deactivation, on the contrary, accelerates the death of irradiated cells. Molecular radiologist Tracy Robson and her team believe that the study of the mechanisms of this gene will help create anti-radiation drugs and drugs that enhance the effectiveness of radiation therapy for malignant tumors.

However, in 1999 The journal publishes ten major scientific breakthroughs in 1998. Three are related to physics (universe, neutrinos, teleportation), one to chemistry (combinatorial chemistry), two to medicine (prevention of cancer, arthritis), and four to biology (time genes, worm genome, nerve impulse movement, biomicrocircuits). Two main physical problems of the last decades are closed - the mass of neutrinos and the scenario of the development of the Universe. The center of scientific interest moves to the field of biology, physiology, and genetics. Since then, genetic science has progressed extremely rapidly.
What scientific breakthroughs do you mean?
Finding in fruit aphids, mice and bacteria genes responsible for time control. The presence of such genes may help explain why many living organisms (including humans) wake up in the morning and fall asleep at night.
Compilation of a complete genetic portrait of one of the complex living creatures - the ringworm Caenorhabdits elegans. Gene maps have also been compiled for a range of microbes, including typhoid, tuberculosis, and syphilis.
This is the last of the discoveries of the year: scientists reported on it on December 10, so a little more about it.
The worm is absolutely tiny - its size is less than a millimeter. He lives in all sorts of dirt and feeds on even smaller bacteria. “In front of us lies a worm folded from millions of pieces,” Robert Waterson from the University of Washington figuratively describes the result of his work. “Now we have to figure out how it all works.” Director of the US National Institutes of Health Harold Varmus is more categorical: "This is a watershed in the history of biology."
For eight years, scientists from the University of Washington in the USA and Cambridge in England have identified and cross-linked with each other about two thousand genes that make up the DNA of the aforementioned worm (more than one hundred million chemical compounds have been decoded). Interestingly, about forty percent of them are similar to the genes of other living organisms. And although the worm (with some similarities) is quite different from Homo sapiens, scientists believe that it will greatly help them in understanding various aspects of human life and disease.
Scientists have isolated six percent of human genes to date and hope to map the human genome completely by 2003.
This was the picture at the beginning of 1999. It was this year that turned out to be the richest in publications devoted to genetics and gene research. This year's publications focus on such problems as mutations, chemical dependence, pharmacogenetics.
American scientists have found that the cause of alcoholism and drug addiction is in damaged genes. A mutating gene creates a tendency to chemical addiction.

The nature of painful overeating is the same as the nature of drug addiction. People from the "risk group" can be found even in the hospital. Soon, medicine will not work with the sick, but with those who can get sick: with risk groups.
The largest research program of the twentieth century in biology (perhaps in science in general) should basically be completed by 2005: by that time the human genome will have been deciphered. Each of the hundreds of thousands of genes will receive a name, an address in the chromosome, which will be included in a single global data bank.
The program is moving very quickly: when we started collecting materials for this theme of the issue, three to four thousand genes were deciphered, on the eve of putting the issue to the printing house - five to ten thousand. How many new names will appear in the catalog of human genes by the time you read these lines?
In the West, the discovery of a new gene is patented because it may be associated with revolutionary prospects in medicine and biotechnology. In our country, of course, no one patents anything - we are generous people.
It is not only the prospect of a technological breakthrough that will undoubtedly begin immediately after the completion of the research phase is breathtaking. After all, knowing how the new gene works will make you look at a person in general, at the nature of his habits, addictions, his way of life, in a completely different way. This is precisely the discovery of American scientists who have established the genetic origin of the tendency to alcoholism and drug addiction, which have always been considered purely social diseases. Understanding how decoded genomes work will lead to the ability to diagnose not diseases, but predispositions to them.
Then the center of all medical work will shift to risk groups.

Why do normal parents in normal families grow up children with deviant behavior? How are behavior and personality traits related to illness? These questions have been asked for a long time, but intelligible answers to them are one of the greatest achievements of our “age of genetics”.
In ordinary schools in America, they began to observe children who differed from the rest in the inability to concentrate, concentrate, disobedience, impulsiveness and increased anxiety. When you talk to them, it seems that they are not listening to you. For them, it's just torture to sit in one place for a long time. Such children cannot wait, whether it is a line at the buffet or a question from the teacher in the lesson. The little patients ran and jumped excessively, fussily and awkwardly, and were not even able to play for a long time. All their games were impulsive, destructive actions. It is not surprising that it was very difficult for them to study, and relations with teachers and peers left much to be desired.
The children suffered from a condition called Attention Deficit Hyperactivity Disorder. This is the most common deviation in childhood, it happens, as researchers have established, in five to eight percent of boys and two to four percent of girls. In half of them, the disease persists throughout life, although in a weakened form. It was possible to find out that attention deficit disorder is also common among the relatives of these children, it has a family, genetic nature. It also turned out that in such families the percentage of alcoholics and people suffering from other types of chemical dependence is much higher than the average. This led to the assumption that attention deficit hyperactivity disorder and alcoholism are caused by the same gene, the action of which manifests itself in childhood as attention deficit disorder, and in adulthood as alcoholism and depression.
The assumption was strengthened after another disease was studied in detail - Tourette's syndrome (TS), a classic genetic pathology that was previously considered quite rare. It manifests itself both in motor tics (rapid blinking, twitching or nodding of the head, grimacing, shrugging, opening the mouth, etc.), and in vocal ones - coughing, clearing the throat, involuntary sounds up to loud screams or squeals. The researchers were particularly struck by the fact that fifty to eighty-five percent of patients showed all the signs of attention deficit hyperactivity disorder. Conversely, it turned out that in families with attention deficit disorder, up to fifty percent of relatives have chronic motor- or vocal-tic pathology. Among patients with TS and their relatives, alcoholics and drug addicts were again found, especially among men, and irresistible overeating with obesity in women. The disease occurs on average in one boy out of ninety.
The conclusion suggested itself: the mutant gene that causes Tourette's syndrome causes other disorders. But again, this was just a guess. And they also found out that children of alcoholics taken away from their parents immediately after birth become alcoholics much more often, although there is no need to talk about the influence of the environment in such cases. One of the pioneers in this field was Donald Goodman. He found that the sons of alcoholic fathers were three times more likely to become alcoholics than the offspring of healthy parents. The difference showed up even when children of alcoholics were raised by healthy foster families. The genetic nature of alcoholism seemed indisputable. And all the results as a whole clearly testified to the genetic nature of not only alcoholism, but also drug addiction and other chemical addictions.
Soon, from the brain tissue of patients with severe toxic forms of alcoholism, two other scientists - Blum and Noble - isolated a mutant gene, the activity of which led to disturbances in the cellular receptors (“receivers”) of dopamine, a substance that works as a “communicator” between different parts of the nervous system. In particular, dopamine plays a key role in the pleasure centers. A genetic defect associated with the breakdown of dopamine receptors was found in sixty-nine percent of heavy alcoholics and only twenty percent of healthy people from the control group.
But this was not yet a victory. The discovered gene acted only as a modifier, an amplifier of the activity of another, not yet known gene, the mutation of which could be the root cause of the disease. The views of researchers turned to systems that connect nerve cells with somatic, bodily ones.
The brain gives commands in the language of electrical impulses, and another language operates inside the cell - chemical. The translator is a structure that connects nerve cells with somatic (bodily) and with each other. This structure is called "synapse" ("connection"). And she carries out the translation with the help of special substances - intermediaries or transmitters. One of the leading transmitters of the brain is serotonin. Its action is associated with mood, emotions, motivations, goal-directed behavior, attention, thinking before doing something ... If the serotonin metabolism is disturbed, the balance of serotonin and dopamine is changed, all these important mental functions will suffer, and the body will begin to look for a way to eliminate unpleasant sensations : there will be a craving for alcohol, drugs, sweets, cigarettes ... In different biochemical ways, nicotine, drugs, alcohol, glucose can temporarily reduce or even completely compensate emotional stress, bad mood, to distract from the feeling of the impossibility of achieving some goal, and healthy people have experienced this themselves.
It turned out that the level of serotonin is stably reduced in patients with Tourette's syndrome and attention deficit disorder. Then a truly detective investigation began, the search for the biochemical culprits of the violation of serotonin metabolism.
The precursor of serotonin is the essential amino acid tryptophan, which we get from food. The enzyme tryptophan oxygenase is involved in its metabolism. Mutation of the tryptophan oxygenase gene leads to an increase in the activity of the enzyme, and hence to a decrease in the level of tryptophan in the body. This, in turn, leads to a decrease in the amount of serotonin, and it is simply not enough to perform all the tasks assigned to it. All this has been found in people with the syndromes we already know.
Cloning of the tryptophan oxygenase gene made it possible to establish its address - the long arm of the fourth chromosome. And then the method of linkage analysis showed that the gene for early alcoholism is located in the same place, in the same locus, this is the same gene!
There is no doubt: the mutation of the open gene is associated with a whole fan of severe behavioral disorders, including drug addiction and alcoholism. They have always been considered different diseases with different causes. Now a fundamentally new concept of chemical dependence has emerged: the idea of ​​it as a spectral pathology. The very phenomenon of spectral pathology, when one mutant gene causes many clinically registered disorders, has long been known in medicine, but it has never been associated with chemical addictions before. The results of recent research have literally revolutionized the views of physicians on alcoholism and drug addiction and have given rise to new concepts of treatment. Today, the key to solving the problem is biochemical correction, the replacement of missing substances and the regulation of their interactions in the body. In addition to serotonin-like drugs, special nutritional supplements and replacement diets have already been developed. To date, seven genes have been discovered, the damage of which is associated with the occurrence of chemical dependence. The problem is getting more complicated.
Literally every month, every quarter, more and more information is accumulated about the colossal genetic diversity of the species Homo sapiens, it is unusually large. This is based on genetic polymorphism - different states of the same gene. Even identical twins are not identical. Thanks to polymorphism, our species is stable in general, it is labile in the environment. In the conditions of modern civilization, human genetic polymorphism manifests itself in different resistance of people to harmful industrial influences.
In our country, there are such industries that have long been banned in civilized countries, for example, the production of asbestos, which was abandoned everywhere precisely because of too “dirty” production. These factories employ a huge number of people, many of them fall ill first with dust bronchitis, then with asbestosis, a serious occupational pulmonary disease that can eventually lead to death. But, fortunately, not everyone suffers such a fate, some of the workers of such enterprises do not get sick with anything, despite the fact that they breathe the same asbestos dust.
In the laboratory of environmental genetics, the question was asked: how is the reaction of people to obviously powerful damaging effects of the environment connected with their genetic structure? As an object of study, they chose this very asbestos production and began to study people with asbestosis, the control group (people from the outside) and those who had worked in this production for many years and absolutely did not get sick. There was a significant difference in the genetic structure of these groups. People have been identified with different gene states, that is, with different alleles. Some gene conditions predispose a person to asbestosis. People carrying this allele have very low levels of the alpha-aminoditrypsin protein and are prone to developing lung disease as a result. If such a person smokes, he dies on average twenty-five years earlier, this is a known fact. On the contrary, there are other gene states that make people resistant to this disease. In Yegoryevsk, at the asbestos production, they found those who were categorically contraindicated for this work. Under normal conditions, not in contact with the dust load, such a person will feel great.
Similar studies were carried out by the Laboratory of Ecological Genetics in other hazardous industries. And now, in case of doubtful cases, its employees, after conducting a genetic analysis, can indicate the cause of a particular occupational disease. The problem of stability or, conversely, predisposition to occupational diseases has been largely resolved, and this, of course, is a great achievement. “I think,” Viktor Alekseevich says, “that in the future they will create a special genetic service that will give recommendations on possible professional activities in terms of predisposition to occupational diseases.”
Among the unresolved problems, one of the most acute is the study of resistance to AIDS. Scientists from different countries are working on it together, here, by the forces of a small team, of course, it is not possible to cope. And here is what is already known. There are mutations that lead to protection against AIDS. This is a fact, and more and more data is accumulating. People with this gene condition can be infected but will not get sick. AIDS has been around for perhaps thousands of years, at least in Africa, from where it spread throughout the world. In countries such as Tanzania, Uganda, among women of easy virtue, the infection rate reaches 60-80 percent; nevertheless, they not only do not die, but also give healthy offspring. Viktor Alekseevich demonstrated a genetic map showing the frequency distribution of this mutant form in Europe. The mutation is quite widespread. The map shows that its frequency is very high among the Finno-Ugric population, it reaches, for example, 16 percent in Finland, 14 percent in Mordovia, all these are people who are immune to the development of AIDS. Death from this disease does not threaten all mankind.
But even existing under normal conditions, a person can be genetically absolutely inadequate to the environment. Viktor Alekseevich also studied ordinary human populations under ordinary conditions. He worked in the Baikal region, studying the alien population and the indigenous Buryat. It turns out that if we divide the population into so-called health groups, in the first of which there are people who are not sick at all, in the fifth - severely disabled, and the rest are intermediate, it turns out that these groups are different in terms of the totality of genetic information. However, those settlers who had genetic characteristics similar to the individual hereditary characteristics of the natives adapted better to the conditions of an unusual geographical environment. Based on genetic analysis, today it is possible to assess the degree of well-being of a particular person in a particular environmental situation.
Perhaps in the future the results of such studies will be taken into account in migration policy. It has been convincingly shown that people with different genotypes react differently to the effects of even a normal environment. Migration activity of the population in our country is now very high, and the problem of individual biological adaptation to new conditions is on a par with all other difficulties. These are just a few examples of how, in practice, knowledge about the human genome can be used.
In the publication of the same year, the idea was voiced that the difference in the genetic structure of individuals could lead to their treatment with various drugs.
Long before the complete decoding of the human genome, researchers in the field of fundamental and applied science began to study more subtle effects: the study of how genetic information changes from one person to another. A database created on the basis of such work will allow us to understand how specific genes affect a variety of diseases. Pharmaceutical and biotech companies plan to use this data to develop specific drugs for different patient populations. Such selectivity can eliminate adverse reactions from drugs and better understand how they work, and along the way, reduce the cost of testing certain drugs in millions and billions.
"Pharmacogenetics" is a new term used to describe the occupation of researchers who are trying to understand how certain features of the structure of DNA can weaken or enhance the effects of a drug, or even turn it into a poison. In 1998, the respected medical journal of the American Medical Association estimated that approximately two million Americans were admitted to the hospital each year, and about one hundred thousand paid with their lives due to misprescribed medications. Thus, inadequate drug treatment comes out on top as a cause of death in the United States.
Many of the ideas of "pharmacogenetics" are not new: scientists have long understood that the response to drugs depends on the genetic structure of the body. For example, a protein called "cytochrome P450" clearly affects the absorption of drugs by the patient. But until recently, such examples were counted in units. Now, the American National Medical Institute has initiated a special three-year program worth $36 million to determine from 50,000 to 100,000 small modifications of the genetic code (SNP - single nucleotide polymorphism - in the jargon of geneticists they are called "snips") that can actively influence the assimilation medicines. By mid-1998, several large pharmaceutical companies were willing to join the program and significantly increase its funding. So far, the agreement has not been signed for one single reason: scientists from the National Medical Institute fear that the involvement of the "big men" of private business may block access to the widest sections of the public to the results of research, and this is unacceptable.
Some private biotech companies, such as Genset in France, are trying to create private databases on their own. DNA testing is being carried out in hundreds of patients, it is planned to create a database of 60,000 snips. Abbot Laboratories, America's premier drug maker, has already invested about $20 million in Genset research. In return, they hope to obtain detailed information about the genetic characteristics of patients who do not respond to certain drugs. Another $22.5 million is dedicated to a specific task: to find the reason why the asthma drug Cyleton causes liver poisoning in three percent of patients. Another pharmaceutical giant, Incyte Pharmaceuticals, has been funding similar studies since August 1998 at the British company Hexagen from Cambridge.
In parallel with genetic research, the development of a quick method for determining the individual genetic portrait of a person is also underway. Conventional genetic sequencing technology requires at least two weeks and twenty thousand dollars to identify one hundred thousand snips in a single patient. This is absolutely unacceptable for real clinical trials. Affymetrix recently announced that it is testing an electronic chip capable of detecting 3,000 snips in less than ten minutes. This means a hundred thousand "snip" required in a few hours and for only a few hundred dollars.
Not everyone needs such a comprehensive genetic picture. The American company "Variagenics" specializes in just a few genes responsible for certain diseases. To find the required "snip", a special protein "resolvase" is "laid" on the DNA. It cuts DNA when it encounters a deviation from the standard sequence, i.e. "snip". So far, Variogenics is tackling a specific challenge: learning how to dose the widely used anti-cancer drug 5-fluorascil, which sometimes causes significant internal damage in patients.
The widespread introduction of the method of genetic dosage of drugs is still far away, and researchers have to overcome many obstacles. First of all, it is beneficial for large companies to produce medicines in large batches in order to justify development costs. In addition, the division of patients into groups can lead to the fact that not everyone will have enough money for treatment. The impetus for the development of "pharmacogenetics" can only be given by state medical control, this will help save taxpayers huge amounts of money, and sometimes even save lives. American programs on ethical, social and other aspects of the "human genome" plan to focus their attention in the next five years on the search for genetic abnormalities.
The new method also has opponents who consider it simply vicious: just as the opinion of sociobiology was fashionable before that all human development is determined by genes, so now there is a danger of exaggerating the omnipotence of the new approach. William Hazeltine, head of the Human Genome Project, believes that testing a drug always depends on many factors: the simultaneous action of several groups of genes, the conditions of the test, the characteristics of the patient. All this must be taken into account, and therefore do not rush to absolutize the results.
No matter how funny it may sound, but genetics has invaded even a field as far from it as the study of the Bible. Again in 1999. "Knowledge is Power" publishes the article "The Bible and Genetics: The Family of Abraham". Let us mention the most interesting facts and conclusions given by the author of the article, where he gives genetic arguments in favor of the earthly reality of Abraham and about the features of the manifestation among his descendants of one rare mutation that causes polar anomalies in the reproduction system - infertility, interspersed with twins. It turns out that the genealogy of Abraham raises questions that are very relevant for medical genetics Geneticist will find a lot of interesting things in the Bible. Among the characters of the Bible, you can find many hereditary variations of the norm and mutants. Among them: six-fingered, excessive hairiness, red hair and baldness, left-handedness, obesity, gout. The scientific description of the variability and inheritance of human traits dates back to the beginning of the 20th century, when Mendel's laws were rediscovered and the chromosome theory appeared. The accumulation of knowledge in this area makes it possible to see the natural background of those biblical events that seemed to have a purely religious meaning.

Achievements and problems of modern genetics. On the basis of genetic research, new areas of knowledge (molecular biology, molecular genetics), relevant biotechnologies (such as genetic engineering) and methods (for example, polymerase chain reaction) have arisen that make it possible to isolate and synthesize nucleotide sequences, integrate them into the genome, and obtain hybrid DNA with properties that do not exist in nature. Many drugs have been obtained, without which medicine is already unthinkable (see GENETIC ENGINEERING). The principles of breeding transgenic plants and animals with characteristics of different species have been developed. It became possible to characterize individuals by many polymorphic DNA markers: microsatellites, nucleotide sequences, etc. Most molecular biological methods do not require hybridological analysis. However, in the study of traits, analysis of markers and mapping of genes, this classical method of genetics is still needed.

Like any other science, genetics has been and remains the weapon of unscrupulous scientists and politicians. Such a branch of it as eugenics, according to which the development of a person is completely determined by his genotype, served as the basis for the creation of racial theories and sterilization programs in the 1930s-1960s. On the contrary, the denial of the role of genes and the acceptance of the idea of ​​the dominant role of the environment led to the cessation of genetic research in the USSR from the late 1940s to the mid-1960s. Now there are ecological and ethical problems in connection with the work on the creation of "chimeras" - transgenic plants and animals, "copying" animals by transplanting the cell nucleus into a fertilized egg, genetic "certification" of people, etc. The leading powers of the world pass laws aimed at preventing undesirable consequences such works.

Modern genetics has provided new opportunities for studying the activity of an organism: with the help of induced mutations, almost any physiological process can be turned off and on, protein biosynthesis in a cell can be interrupted, morphogenesis can be changed, and development can be stopped at a certain stage. We can now delve deeper into population and evolutionary processes (see POPULATION GENETICS), study hereditary diseases (see GENETIC COUNSELING), the problem of cancer, and much more. In recent years, the rapid development of molecular biological approaches and methods has allowed geneticists not only to decipher the genomes of many organisms, but also to design living beings with desired properties. Thus, genetics opens up ways to model biological processes and contributes to the fact that biology, after a long period of fragmentation into separate disciplines, enters an era of unification and synthesis of knowledge.

Introduction………………………………………………………………………3

Chapter 1. The subject of genetics……………………………………………....4

1.1 What does genetics study……………………………………………....4

1.2. Modern ideas about the gene…………………………….5

1.2. Gene structure……………………………………………………...6

1.4. Problems and methods of genetics research…………………9

1.5. The main stages in the development of genetics…………………………..11

1.6 Genetics and man……………………………………………….18

Chapter 2. The role of reproduction in the development of the living……………. 23

2.1. Features of cyclic reproduction……………23

Conclusion………………………………………………………...27

Bibliographic list of used literature…………….…29

Introduction

For my work on the subject “Concepts of modern natural science”, I chose the topic “Main problems of genetics and the role of reproduction in the development of the living”, because genetics is one of the main, most fascinating and at the same time complex disciplines of modern natural science.

Genetics, which turned the biology of the 20th century into an exact scientific discipline, continuously strikes the imagination of the “broad sections” of the scientific and pseudo-scientific community with new directions and more and more new discoveries and achievements. For thousands of years, man has used genetic methods to improve the useful properties of cultivated plants and breed highly productive breeds of domestic animals, without understanding the mechanisms underlying these methods.

Only at the beginning of the  century did scientists begin to fully realize the importance of the laws of heredity and its mechanisms. Although the advances in microscopy made it possible to establish that hereditary traits are transmitted from generation to generation through spermatozoa and ova, it remained unclear how the smallest particles of protoplasm could carry the “ingredients” of the vast array of traits that make up each individual organism.

Chapter 1. The subject of genetics

1.1 What does genetics study.

Genetics is the science of heredity and variation in organisms. Genetics is a discipline that studies the mechanisms and patterns of heredity and variability of organisms, methods for managing these processes. It is designed to reveal the laws of reproduction of the living by generations, the emergence of new properties in organisms, the laws of individual development of an individual and material basis historical transformations of organisms in the process of evolution.

Depending on the object of study, plant genetics, animal genetics, microorganism genetics, human genetics, etc. are distinguished, and depending on the methods used in other disciplines, biochemical genetics, molecular genetics, ecological genetics, etc.

Genetics makes a huge contribution to the development of the theory of evolution (evolutionary genetics, population genetics). Ideas and methods of genetics are used in all areas of human activity related to living organisms. They are important for solving problems in medicine, agriculture, and the microbiological industry. The latest advances in genetics are associated with the development of genetic engineering.

In modern society, genetic issues are widely discussed in different audiences and from different points of view, including ethical, obviously, for two reasons.

The need to understand the ethical aspects of the use of new technologies has always arisen.

The difference of the modern period is that the speed of the implementation of an idea or scientific development as a result has increased dramatically.

1.2. Modern ideas about the gene.

The role of genes in the development of an organism is enormous. Genes characterize all the signs of a future organism, such as eye and skin color, size, weight, and much more. Genes are carriers of hereditary information on the basis of which the organism develops.

Just as in physics the elementary units of matter are atoms, in genetics the elementary discrete units of heredity and variability are genes. The chromosome of any organism, be it a bacterium or a human, contains a long (hundreds of thousands to billions of base pairs) continuous DNA chain along which many genes are located. Establishing the number of genes, their exact location on the chromosome, and the detailed internal structure, including knowledge of the complete nucleotide sequence, is a task of exceptional complexity and importance. Scientists successfully solve it using a whole range of molecular, genetic, cytological, immunogenetic and other methods.

1.2. The structure of the gene.

Coding chain

Regulatory zone

promoter

Exon 1

promoter

promoter

promoter

Intron 1

Exon 2

promoter

Exon 3

Intron2

Terminator

i-RNA

Transcription

Splicing

Mature mRNA

According to modern concepts, the gene encoding the synthesis of a certain protein in eukaryotes consists of several mandatory elements. (Fig) First of all, it is an extensive regulatory a zone that has a strong influence on the activity of a gene in a particular tissue of the body at a certain stage of its individual development. Next is the promoter directly adjacent to the coding elements of the gene -

a DNA sequence up to 80-100 base pairs long, responsible for binding the RNA polymerase that transcribes the given gene. Following the promoter lies the structural part of the gene, which contains information about the primary structure of the corresponding protein. This region for most eukaryotic genes is significantly shorter than the regulatory zone, but its length can be measured in thousands of base pairs.

An important feature of eukaryotic genes is their discontinuity. This means that the region of the gene encoding the protein consists of two types of nucleotide sequences. Some - exons - sections of DNA that carry information about the structure of the protein and are part of the corresponding RNA and protein. Others - introns - do not encode the structure of the protein and are not included in the composition of the mature mRNA molecule, although they are transcribed. The process of cutting out introns - "unnecessary" sections of the RNA molecule and splicing of exons during the formation of mRNA is carried out by special enzymes and is called splicing(stitching, splicing). Exons are usually joined together in the same order as they are in DNA. However, not all eukaryotic genes are discontinuous. In other words, in some genes, like bacteria, there is a complete correspondence of the nucleotide sequence to the primary structure of the proteins they encode.

1.3. Basic concepts and methods of genetics.

Let us introduce the basic concepts of genetics. When studying the patterns of inheritance, individuals are usually crossed that differ from each other in alternative (mutually exclusive) traits (for example, yellow and green, smooth and wrinkled surface of peas). The genes that determine the development of alternative traits are called allelic. They are located in the same loci (places) of homologous (paired) chromosomes. An alternative trait and the gene corresponding to it, which appears in hybrids of the first generation, are called dominant, and not manifested (suppressed) are called recessive. If both homologous chromosomes contain the same allelic genes (two dominant or two recessive), then such an organism is called homozygous. If different genes of the same allelic pair are localized in homologous chromosomes, then such an organism is called heterozygous on this sign. It forms two types of gametes and, when crossed with an organism of the same genotype, gives splitting.

The totality of all the genes in an organism is called genotype. A genotype is a set of genes that interact with each other and influence each other. Each gene is affected by other genes of the genotype and itself affects them, so the same gene in different genotypes can manifest itself in different ways.

The totality of all the properties and characteristics of an organism is called phenotype. The phenotype develops on the basis of a certain genotype as a result of interaction with environmental conditions. Organisms that have the same genotype may differ from each other depending on the conditions.

Representatives of any biological species reproduce creatures similar to themselves. This property of descendants to be similar to their ancestors is called heredity.

Features of the transmission of hereditary information are determined by intracellular processes: mitosis and meiosis. Mitosis- This is the process of distribution of chromosomes to daughter cells during cell division. As a result of mitosis, each chromosome of the parent cell is duplicated and identical copies diverge to the daughter cells; in this case, hereditary information is completely transmitted from one cell to two daughter cells. This is how cell division occurs in ontogenesis, i.e. the process of individual development. Meiosis- This is a specific form of cell division, which takes place only during the formation of germ cells, or gametes (spermatozoa and eggs). Unlike mitosis, the number of chromosomes during meiosis is halved; only one of the two homologous chromosomes of each pair gets into each daughter cell, so that in half of the daughter cells there is one homologue, in the other half - the other; while chromosomes are distributed in gametes independently of each other. (The genes of mitochondria and chloroplasts do not follow the law of equal distribution during division.) When two haploid gametes merge (fertilization), the number of chromosomes is restored again - a diploid zygote is formed, which received a single set of chromosomes from each parent.

Despite the enormous influence of heredity in shaping the phenotype of a living organism, related individuals differ to a greater or lesser extent from their parents. This property of descendants is called variability. The science of genetics deals with the study of the phenomena of heredity and variability. Thus, genetics is the science of the laws of heredity and variability. According to modern concepts, heredity is the property of living organisms to transmit from generation to generation features of morphology, physiology, biochemistry and individual development under certain environmental conditions. Variability- a property opposite to heredity is the ability of daughter organisms to differ from their parents in morphological, physiological, biological characteristics and deviations in individual development.

The study of phenotypic differences in any large population shows that there are two forms of variability - discrete and continuous. To study the variability of a trait, such as height in humans, it is necessary to measure that trait in a large number of individuals in the population under study.

Heredity and variability are realized in the process of inheritance, i.e. when transferring genetic information from parents to offspring through germ cells (during sexual reproduction) or through somatic cells (during asexual reproduction Today, genetics is a single complex science that uses both biological and physico-chemical methods to solve the widest range of the largest biological problems.

1.4. Problems and methods of genetics research.

The global fundamental issues of modern genetics include the following problems:

1. The variability of the hereditary apparatus of organisms (mutagenesis, recombinogenesis, and directional variability), which plays an important role in breeding, medicine, and the theory of evolution.

2. Environmental problems associated with the genetic consequences of chemical and radiation pollution of the environment surrounding people and other organisms.

3. Growth and reproduction of cells and their regulation, formation of a differentiated organism from one cell and control of development processes; cancer problem.

4. The problem of body protection, immunity, tissue compatibility during tissue and organ transplantation.

5. The problem of aging and longevity.

6. The emergence of new viruses and the fight against them.

7. Particular genetics of different types of plants, animals and microorganisms, which makes it possible to identify and isolate new genes for use in biotechnology and breeding.

8. The problem of productivity and quality of agricultural plants and animals, their resistance to adverse environmental conditions, infections and pests.

To solve these problems, different research methods are used.

Method hybridological analysis was developed by Gregor Mendel. This method makes it possible to reveal patterns of inheritance of individual traits during sexual reproduction of organisms. Its essence is as follows: the analysis of inheritance is carried out on separate independent traits; transmission of these signs in a number of generations is traced; an accurate quantitative account is taken of the inheritance of each alternative trait and the nature of the offspring of each hybrid separately.

Cytogenetic method allows you to study the karyotype (set of chromosomes) of body cells and identify genomic and chromosomal mutations.

genealogical method involves the study of pedigrees of animals and humans and allows you to establish the type of inheritance (for example, dominant, recessive) of a particular trait, the zygosity of organisms and the likelihood of manifestation of traits in future generations. This method is widely used in breeding and the work of medical genetic consultations.

twin method based on the study of the manifestation of signs in identical and dizygotic twins. It allows you to identify the role of heredity and the environment in the formation of specific traits.

Biochemical methods studies are based on the study of the activity of enzymes and the chemical composition of cells, which are determined by heredity. Using these methods, it is possible to identify gene mutations and heterozygous carriers of recessive genes.

Population-statistical method allows you to calculate the frequency of occurrence of genes and genotypes in populations.

development and existence. A single feature is called hair dryer. Phenotypic features include not only external features (eye color, hair, nose shape, flower color, etc.), but also anatomical (stomach volume, liver structure, etc.), biochemical (glucose and urea concentration in blood serum, etc.). ) and others.

1.5. The main stages in the development of genetics.

The origins of genetics, like any science, should be sought in practice. Genetics arose in connection with the breeding of domestic animals and the cultivation of plants, as well as with the development of medicine. Since man began to use the crossing of animals and plants, he was faced with the fact that the properties and characteristics of the offspring depend on the properties of the parent individuals chosen for crossing.

The development of the science of heredity and variability was especially strongly promoted by Charles Darwin's theory of the origin of species, which introduced the historical method of studying the evolution of organisms into biology. Darwin himself put a lot of effort into the study of heredity and variability. He collected a huge amount of facts, made a number of correct conclusions on their basis, but he failed to establish the laws of heredity. His contemporaries, the so-called hybridizers, who crossed various forms and looked for the degree of similarity and difference between parents and offspring, also failed to establish general patterns of inheritance.

First a truly scientific step forward in the study of heredity was made by the Austrian monk Gregor Mendel (1822-1884), who in 1866 published an article that laid the foundations of modern genetics. Mendel showed that hereditary inclinations do not mix, but are transmitted from parents to descendants in the form of discrete (isolated) units. These units, presented in pairs in individuals, remain discrete and are passed on to subsequent generations in male and female gametes, each of which contains one unit from each pair.

Summary of the essence of Mendel's hypotheses

1. Each feature of a given organism is controlled by a pair of alleles.

2. If the organism contains two different alleles for a given trait, then one of them (dominant) can manifest itself, completely suppressing the manifestation of another trait (recessive).

3. During meiosis, each pair of alleles is divided (splitting) and each gamete receives one of each pair of alleles (splitting principle).

4. During the formation of male and female gametes, any allele from one pair can get into each of them along with any other from the other pair (principle of independent distribution).

5. Each allele is passed from generation to generation as a discrete unit that does not change.

6. Each organism inherits one allele (for each trait) from each of the parent individuals.

For the theory of evolution, these principles were of cardinal importance. They uncovered one of the most important sources of variability, namely, the mechanism for maintaining the fitness of the traits of a species in a number of generations. If the adaptive traits of organisms, which arose under the control of selection, were absorbed, disappeared during crossing, then the progress of the species would be impossible.

All subsequent development of genetics has been associated with the study and extension of these principles and their application to the theory of evolution and selection.

On the second stage August Weisman (1834-1914) showed that germ cells are isolated from the rest of the organism and therefore are not subject to influences acting on somatic tissues.

Despite Weismann's convincing experiments, which were easy to verify, Lysenko's victorious supporters in Soviet biology long denied genetics, calling it Weismannism-Morganism. In this case, ideology won over science, and many scientists, such as N.I. Vavilov, were repressed.

On the third stage Hugo de Vries (1848-1935) discovered the existence of heritable mutations that form the basis of discrete variability. He suggested that new species arose due to mutations.

Mutations are partial changes in the structure of a gene. Its final effect is a change in the properties of proteins encoded by mutant genes. The trait that appeared as a result of a mutation does not disappear, but accumulates. Mutations are caused by radiation, chemical compounds, temperature changes, and may simply be random.

On the fourth Thomas Maughan (1866-1945) created the chromosome theory of heredity, according to which each biological species has a strictly defined number of chromosomes.

On the fifth stage G. Meller in 1927 found that the genotype can change under the influence of x-rays. This is where induced mutations originate, and what was later called genetic engineering with its grandiose possibilities and dangers of interfering with the genetic mechanism.

On the sixth stage J. Beadle and E. Tatum in 1941 revealed the genetic basis of biosynthesis.

On the seventh At the stage, James Watson and Francis Crick proposed a model of the molecular structure of DNA and the mechanism of its replication. They found that each DNA molecule is made up of two polydeoxyribonucleic chains, spirally twisted around a common axis.

In the period from the 1940s to the present, a number of discoveries (mainly on microorganisms) of completely new genetic phenomena have been made, which have opened up the possibilities of analyzing the structure of a gene at the molecular level. In recent years, with the introduction of new research methods into genetics, borrowed from microbiology, we have come to unravel how genes control the sequence of amino acids in a protein molecule.

First of all, it should be said that it has now been fully proven that the carriers of heredity are chromosomes, which consist of a bundle of DNA molecules.

Quite simple experiments were carried out: from the killed bacteria of one strain, which had a special external feature, pure DNA was isolated and transferred to living bacteria of another strain, after which the multiplying bacteria of the latter acquired the feature of the first strain. Such numerous experiments show that it is DNA that is the carrier of heredity.

At present, approaches have been found to solving the problem of organizing the hereditary code and its experimental decoding. Genetics, together with biochemistry and biophysics, came close to elucidating the process of protein synthesis in a cell and the artificial synthesis of a protein molecule. This begins a completely new stage in the development of not only genetics, but of all biology as a whole.

The development of genetics to the present day is a continuously expanding fund of research on the functional, morphological and biochemical discreteness of chromosomes. A lot has already been done in this area, a lot has already been done, and every day the cutting edge of science is approaching the goal - unraveling the nature of the gene. To date, a number of phenomena characterizing the nature of the gene have been established. First, the gene in the chromosome has the property of self-reproducing (self-reproduction); secondly, it is capable of mutational change; thirdly, it is associated with a certain chemical structure of deoxyribonucleic acid - DNA; fourthly, it controls the synthesis of amino acids and their sequences in a protein molecule. In connection with recent studies, a new understanding of the gene as a functional system is being formed, and the effect of the gene on determining traits is considered in an integral system of genes - the genotype.

The opening prospects for the synthesis of living matter attract great attention of geneticists, biochemists, physicists and other specialists.

Over the past decades, a qualitative change in genetics as a science has taken place: a new research methodology has emerged - genetic engineering, which has revolutionized genetics and led to the rapid development of molecular genetics and genetically engineered biotechnology.

The modern development of general and particular genetics, molecular genetics and genetic engineering occurs with mutual enrichment of ideas and methods and is compiled by purely genetic analysis, i.e. obtaining mutations and carrying out certain crosses. It was possible to reveal many fundamental laws of life, i.e. already in the early stages of its development, genetics became an exact experimental science.

Without highly developed general and molecular genetics, there can be no effective progress in practically any area of ​​modern biology, breeding, or the protection of the hereditary health of people.

Equally important is genetics and genetic engineering in the development of the national economy.

Modern breeding uses the methods of induced mutations and recombinations, heterosis, polyploidy, immunogenetics, cell engineering, distant hybridization, protein and DNA markers, and others. Their introduction in breeding centers is extremely fruitful.

Currently, industrial microbiological synthesis of a number of products necessary for medicine, agriculture and industry is carried out by genetic engineering. Synthesis of other valuable products is carried out in cell cultures.

The development of microbial genetics largely determines the effectiveness of the microbiological industry.

Now a new stage in the development of genetic engineering is being planned - a transition to the use as sources of valuable products of plants and animals with transplanted genes responsible for the synthesis of the corresponding products, i.e. creation and use of transgenic plants and animals. By creating transgenic organisms, the problems of obtaining new varieties of plants and animal breeds with increased productivity, as well as resistance to infectious diseases and adverse environmental conditions, will also be solved.

The development of genetic engineering has created a fundamentally new basis for constructing DNA sequences that researchers need. Advances in experimental biology have made it possible to develop methods for inserting such engineered genes into the nuclei of eggs or sperm. As a result, it became possible to obtain transgenic animals, those. animals carrying foreign genes in their bodies.

One of the first examples of the successful creation of transgenic animals was the production of mice in the genome of which the rat growth hormone was inserted. Some of these transgenic mice grew rapidly and reached sizes significantly larger than control animals.

The world's first genetically modified monkey was born in America. The male, named Andy, was born after the jellyfish gene was introduced into his mother's egg. The experiment was carried out with the rhesus monkey, which is much closer in its biological characteristics to humans than any other animals that have so far been subjected to experiments on genetic modification. The scientists say the application of this method will help them develop new treatments for diseases such as breast cancer and diabetes. However, according to the BBC, the experiment has already drawn criticism from animal welfare organizations, who fear that the research will lead to the suffering of many primates in laboratories.

Creation of a hybrid of man and pig. The nucleus is extracted from a human cell and implanted into the nucleus of a pig egg, which was previously freed from the genetic material of the animal. The result was an embryo that lived for 32 days before scientists decided to destroy it. Research is carried out, as always, for the sake of a noble goal: the search for cures for human diseases. Although attempts to clone human beings are frowned upon by many scientists and even those who created Dolly the Sheep, such experiments will be difficult to stop, since the principle of the cloning technique is already known to many laboratories.

Currently, interest in transgenic animals is very high. This is due to two reasons. First, ample opportunities have arisen for studying the work of a foreign gene in the genome of a host organism, depending on the place of its integration into one or another chromosome, as well as the structure of the gene regulatory zone. Secondly, transgenic farm animals may be of practical interest in the future.

Of great importance for medicine is the development of methods for prenatal diagnosis of genetic defects and those structural features of the human genome that contribute to the development of serious diseases: cancer, cardiovascular, mental and others.

The task was set to create national and global genetic monitoring, i.e. tracking the genetic load and the dynamics of genes in the heritage of people. This will be of great importance for assessing the impact of environmental mutagens and controlling demographic processes.

The development of methods for correcting genetic defects by gene transplantation (hemotherapy) begins and will be developed in the 90s.

Achievements in the field of studying the functioning of various genes will make it possible in the 1990s to approach the development of rational methods for the treatment of tumor, cardiovascular, a number of viral and other dangerous human and animal diseases.

1.6 Genetics and man.

In human genetics, there is a clear connection between scientific research and ethical issues, as well as the dependence of scientific research on the ethical meaning of their final results. Genetics has stepped so far forward that man is on the threshold of such power that allows him to determine his biological fate. That is why the use of all the potential possibilities of medical genetics is real only with strict observance of ethical standards.

Human genetics, rapidly developing in recent decades, has provided answers to many of the questions people have long been interested in: what determines the sex of a child? Why do children look like their parents? What signs and diseases are inherited and which are not, why people are so different from each other, why are closely related marriages harmful?

Interest in human genetics is due to several reasons. First, it is the natural desire of man to know himself. Secondly, after many infectious diseases were defeated - plague, cholera, smallpox, etc. - the relative share of hereditary diseases increased. Thirdly, after the nature of mutations and their significance in heredity were understood, it became clear that mutations can be caused by environmental factors that had not previously been given due attention. An intensive study of the effects of radiation and chemicals on heredity began. Every year, more and more chemical compounds are used in everyday life, agriculture, food, cosmetic, pharmacological industries and other areas of activity, among which many mutagens are used.

In this regard, the following main problems of genetics can be distinguished.

Hereditary diseases and their causes. Hereditary diseases can be caused by disorders in individual genes, chromosomes or sets of chromosomes. For the first time, a connection between an abnormal set of chromosomes and sharp deviations from normal development was discovered in the case of Down syndrome.

In addition to chromosomal disorders, hereditary diseases can be caused by changes in genetic information directly in the genes.

Effective treatments for hereditary diseases do not yet exist. However, there are methods of treatment that alleviate the condition of patients and improve their well-being. They are based mainly on the compensation of metabolic defects caused by disturbances in the genome.

Medical genetic laboratories. Knowledge of human genetics makes it possible to determine the probability of the birth of children suffering from hereditary diseases in cases where one or both spouses are sick or both parents are healthy, but hereditary diseases were found in their ancestors. In some cases, it is possible to predict the birth of a healthy second child if the first one was sick. Such forecasting is carried out in medical genetic laboratories. The widespread use of genetic counseling will save many families from the misfortune of having sick children.

Are abilities inherited? Scientists believe that every person has a grain of talent. Talent is developed through hard work. Genetically, a person is richer in his capabilities, but does not fully realize them in his life.
Until now, there are still no methods for revealing the true abilities of a person in the process of his childhood and youth upbringing, and therefore often the appropriate conditions for their development are not provided.

Does natural selection work in human society? The history of mankind is a change in the genetic structure of populations of the Homo sapiens species under the influence of biological and social factors. Wars, epidemics changed the gene pool of mankind. Natural selection has not weakened over the past 2,000 years, but has only changed: it has been overlaid with social selection.

Genetic Engineering uses the most important discoveries of molecular genetics to develop new research methods, obtain new genetic data, as well as in practical activities, in particular in medicine.

Previously, vaccines were made only from killed or weakened bacteria or viruses capable of inducing immunity in humans through the formation of specific antibody proteins. Such vaccines lead to the development of strong immunity, but they also have disadvantages.

It is safer to vaccinate with pure proteins of the shell of viruses - they cannot multiply, tk. they do not have nucleic acids, but they cause the production of antibodies. They can be obtained by genetic engineering. Such a vaccine against infectious hepatitis (Botkin's disease) has already been created - a dangerous and intractable disease. Work is underway to create pure vaccines against influenza, anthrax and other diseases.

Floor correction. Sex reassignment operations in our country began to be done about 30 years ago strictly for medical reasons.

Organ transplant. Organ transplantation from donors is a very complex operation, followed by an equally difficult period of transplant engraftment. Very often the transplant is rejected and the patient dies. Scientists hope that these problems can be solved with the help of cloning.

Cloning- a method of genetic engineering in which descendants are obtained from the somatic cell of the ancestor and therefore have exactly the same genome.

Animal cloning solves many problems in medicine and molecular biology, but at the same time creates many social problems.

Scientists see the prospect of reproducing individual tissues or organs of seriously ill people for subsequent transplantation - in this case, there will be no problems with transplant rejection. Cloning can also be used to obtain new drugs, especially those obtained from tissues and organs of animals or humans.

However, despite the tempting prospects, the ethical side of cloning is a concern.

Deformities. The development of a new living being occurs in accordance with the genetic code recorded in the DNA, which is contained in the nucleus of every cell in the body. Sometimes, under the influence of environmental factors - radioactive, ultraviolet rays, chemicals - a violation of the genetic code occurs, mutations occur, deviations from the norm.

Genetics and criminalistics. In judicial practice, cases of establishing kinship are known, when children were mixed up in the maternity hospital. Sometimes this concerned children who grew up in foreign families for more than one year. To establish kinship, methods of biological examination are used, which is carried out when the child is 1 year old and the blood system stabilizes. A new method has been developed - gene fingerprinting, which allows analysis at the chromosomal level. In this case, the age of the child does not matter, and the relationship is established with a 100% guarantee.

Chapter 2. The role of reproduction in the development of the living.

2.1. Features of cyclic reproduction.

All stages in the life of any living being are important, including for humans. All of them are reduced to the cyclic reproduction of the original living organism. And this process of cyclic reproduction began about 4 billion years ago.

Let's consider its features. It is known from biochemistry that many reactions of organic molecules are reversible. For example, amino acids are synthesized into protein molecules that can be broken down into amino acids. That is, under the influence of any influences, both synthesis reactions and splitting reactions occur. In living nature, any organism goes through cyclic stages of splitting the original organism and reproduction from the separated part of a new copy of the original organism, which then again gives rise to an embryo for reproduction. It is for this reason that interactions in living nature last continuously for billions of years. The property of reproduction from the split parts of the original organism of its copy is determined by the fact that a complex of molecules is transferred to the new organism, which completely controls the process of recreating the copy.

The process began with the self-reproduction of complexes of molecules. And this path is quite well fixed in every living cell. Scientists have long paid attention to the fact that in the process of embryogenesis, the stages of the evolution of life are repeated. But then you should pay attention to the fact that in the very depths of the cell, in its nucleus, there are DNA molecules. This is the best evidence that life on Earth began with the reproduction of complexes of molecules that had the property of first splitting the DNA double helix, and then providing the process of recreating the double helix. This is the process of cyclic reconstruction of a living object with the help of molecules that were transmitted at the moment of splitting and which completely controlled the synthesis of a copy of the original object. So the definition of life would look like this. Life is a type of interaction of matter, the main difference of which from the known types of interactions is the storage, accumulation and copying of objects that introduce certainty into these interactions and transfer them from random to regular ones, while a cyclic reproduction of a living object occurs.

Any living organism has a genetic set of molecules that completely determines the process of recreating a copy of the original object. That is, in the presence of the necessary nutrients with a probability of one, as a result of the interaction of a complex of molecules, a copy of a living organism will be recreated. But the supply of nutrients is not guaranteed, and harmful external influences and disruption of interactions within the cell also occur. Therefore, the total probability of recreating a copy is always slightly less than one. So, from two organisms or living objects, the organism that has a greater total probability of implementing all the necessary interactions will be copied more efficiently. This is the law of evolution of living nature. In other words, it can also be formulated as follows: the more interactions necessary for copying an object are controlled by the object itself, the greater the probability of its cyclic reproduction.

Obviously, if the total probability of all interactions increases, then the given object evolves; if it decreases, then it involutes; if it does not change, then the object is in a stable state.

The most important function of life activity is the function of self-production. In other words, life activity is the process of satisfying the need for the reproduction by a person of his living being within the framework of the system in which he is included as an element, i.e. in environmental conditions. Taking as an initial thesis the premise that life activity has the most important need for the reproduction of its subject, as the owner of the human body, it should be noted that reproduction is carried out in two ways: firstly, in the process of consuming matter and energy from the environment, and secondly, in the process of biological reproduction, that is, the birth of offspring. The first type of realization of the need in the “environment-organism” link can be expressed as the reproduction of “living from non-living”. Man exists on earth thanks to the constant consumption of the necessary substances and energy from the environment.

IN AND. Vernadsky in his well-known work "Biosphere" presented the process of life on Earth as a constant circulation of matter and energy, in which, along with other creatures, man must be included. Atoms and molecules of physical substances that make up the Earth's biosphere have been included in and out of its circulation millions of times during the existence of life. The human body is not identical to the substance and energy consumed from the external environment, it is the object of its life activity transformed in a certain way. As a result of the realization of the needs for substances, energy, information, another object of nature arises from one object of nature, which has properties and functions that are not at all inherent in the original object. This manifests a special type of activity inherent in man. Such activity can be defined as a need aimed at material and energy reproduction. The content of the realization of this need is the extraction of means of life from the environment. Extraction in a broad sense, both actual extraction and production.

This type of reproduction is not the only one necessary for the existence of life. V.I.Vernadsky wrote that a living organism, “when dying, living and being destroyed, gives it its atoms and continuously takes them from it, but a living substance embraced by life always has a beginning in the living”. The second type of reproduction is also inherent in all living things on Earth. Science has proved with sufficient certainty that the direct origin of living things from inanimate matter at this stage of the Earth's development is impossible.

After the emergence and spread of life on Earth, its emergence at the present time on the basis of inorganic matter alone is no longer possible. All living systems that exist on Earth now arise either on the basis of the living, or through the living. Thus, before a living organism reproduces itself materially and energetically, it must be reproduced biologically, that is, be born by another living organism. The reproduction of the living by the living is, first of all, the transfer by one generation to another of genetic material, which determines in the offspring the phenomenon of a certain morphophysiological structure. It is clear that the genetic material is not transmitted from generation to generation on its own, its transmission is also a function of human life.

Conclusion.

Genetics is the science of heredity and variation in organisms. Genetics is a discipline that studies the mechanisms and patterns of heredity and variability of organisms, methods for managing these processes. It is designed to reveal the laws of reproduction of the living by generations, the emergence of new properties in organisms, the laws of individual development of an individual and the material basis of the historical transformations of organisms in the process of evolution. The objects of genetics are viruses, bacteria, fungi, plants, animals and humans. Against the background of species and other specificity, general laws are found in the phenomena of heredity for all living beings. Their existence shows the unity of the organic world.

In modern society, genetic issues are widely discussed in different audiences and from different points of view, including ethical, obviously, for two reasons.

Firstly, genetics affects the most primary properties of living nature, as if the key positions in life manifestations. Therefore, the progress of medicine and biology, as well as all expectations from it, is often focused on genetics. To a large extent, this focus is justified.

Secondly, in recent decades, genetics has been developing so rapidly that it gives rise to both scientific and quasi-scientific promising forecasts. This is especially true of human genetics, whose progress raises ethical problems more acutely than in other areas of biomedical science.

In human genetics, there is a clear connection between scientific research and ethical issues, as well as the dependence of scientific research on the ethical meaning of their final results. Genetics has stepped so far forward that man is on the threshold of such power that allows him to determine his biological fate. That is why the use of all the potential possibilities of genetics is real only with strict observance of ethical standards.

Genetics occupies an important place in the system of modern sciences, and, perhaps, the most important achievements of the last decade of the past century are connected precisely with genetics. Now, at the beginning of the 21st century, prospects are opening up before humanity that fascinate the imagination. Will scientists be able to realize the gigantic potential inherent in genetics in the near future? Will humanity receive the long-awaited deliverance from hereditary diseases, will a person be able to extend his too short life, gain immortality? At present, we have every reason to hope so.

Bibliographic list of used literature:

Artyomov A. What is a gene. - Taganrog.: Publishing house "Red Page", 1989.

Biological encyclopedic dictionary. - M.: Sov. encyclopedia, 1989.

Vernadsky V.I. Chemical structure of the biosphere of the Earth and its environment. - M .: Nauka, 1965.

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2. Genetics. Lecture notes

   Synopsis >> Biology

   ... role genetics V development medicine. Main sections of modern genetics are: cytogenetics, molecular genetics, mutagenesis, population, evolutionary and ecological genetics ...