What literature for the exam in biology. George Lerner - Biology. A complete guide to preparing for the exam
This handbook contains all the theoretical material on the biology course required to pass the exam. It includes all elements of the content, checked by control and measuring materials, and helps to generalize and systematize knowledge and skills for the course of the secondary (complete) school. The theoretical material is presented in a concise, accessible form. Each section is accompanied by examples of test tasks that allow you to test your knowledge and the degree of preparedness for the certification exam. Practical tasks correspond to the USE format. At the end of the manual, answers to tests are given that will help schoolchildren and applicants to test themselves and fill in the gaps. The manual is addressed to schoolchildren, applicants and teachers.
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The following excerpt from the book Biology. A complete guide to preparing for the exam (G. I. Lerner, 2009) provided by our book partner - the company LitRes.
Cell as a biological system
2.1. Cell theory, its main provisions, role in the formation of the modern natural-science picture of the world. Development of knowledge about the cell. The cellular structure of organisms, the similarity of the structure of the cells of all organisms - the basis of the unity of the organic world, evidence of the relationship of living nature
unity of the organic world, cell, cellular theory, provisions of the cellular theory.
We have already said that a scientific theory is a generalization of scientific data about the object of study. This fully applies to the cell theory created by two German researchers M. Schleiden and T. Schwann in 1839.
The cellular theory was based on the work of many researchers who were looking for an elementary structural unit of the living. The creation and development of cell theory was facilitated by the emergence in the 16th century. and further development of microscopy.
Here are the main events that became the forerunners of the creation of the cell theory:
- 1590 - the creation of the first microscope (Jansen brothers);
- 1665 Robert Hooke - the first description of the microscopic structure of the cork of the elderberry branch (in fact, these were cell walls, but Hooke introduced the name "cell");
- 1695 Anthony Leeuwenhoek's publication on microbes and other microscopic organisms he saw through a microscope;
- 1833 R. Brown described the nucleus of a plant cell;
– 1839 M. Schleiden and T. Schwann discovered the nucleolus.
The main provisions of modern cell theory:
1. All simple and complex organisms consist of cells capable of exchanging substances, energy, and biological information with the environment.
2. A cell is an elementary structural, functional and genetic unit of the living.
3. A cell is an elementary unit of reproduction and development of living things.
4. In multicellular organisms, cells are differentiated in structure and function. They are combined into tissues, organs and organ systems.
5. A cell is an elementary, open living system capable of self-regulation, self-renewal and reproduction.
Cell theory has evolved thanks to new discoveries. In 1880, Walter Flemming described chromosomes and the processes that take place in mitosis. Since 1903, genetics began to develop. Beginning in 1930, electron microscopy began to develop rapidly, which allowed scientists to study the finest structure of cellular structures. The 20th century was the heyday of biology and such sciences as cytology, genetics, embryology, biochemistry, and biophysics. Without the creation of the cell theory, this development would have been impossible.
So, the cell theory states that all living organisms are made up of cells. A cell is that minimal structure of a living thing that has all the vital properties - the ability to metabolism, growth, development, transfer of genetic information, self-regulation and self-renewal. The cells of all organisms have similar structural features. However, cells differ from each other in their size, shape, and function. An ostrich egg and a frog egg are made up of the same cell. Muscle cells have contractility, and nerve cells conduct nerve impulses. Differences in the structure of cells largely depend on the functions they perform in organisms. The more complex the organism is, the more diverse in structure and functions of its cells. Each type of cell has a specific size and shape. The similarity in the structure of the cells of various organisms, the commonality of their basic properties confirm the commonality of their origin and allow us to conclude that the organic world is united.
2.2. A cell is a unit of structure, life activity, growth and development of organisms. variety of cells. Comparative characteristics of cells of plants, animals, bacteria, fungi
Main bacterial cells, fungal cells, plant cells, animal cells, prokaryotic cells, eukaryotic cells.
The science that studies the structure and function of cells is called cytology . We have already said that cells can differ from each other in form, structure and function, although the basic structural elements of most cells are similar. Biologists distinguish two large systematic groups of cells - prokaryotic and eukaryotic . Prokaryotic cells do not contain a true nucleus and a number of organelles. (See the Cell Structure section.) Eukaryotic cells contain a nucleus in which the hereditary apparatus of the body is located. Prokaryotic cells are cells of bacteria, blue-green algae. The cells of all other organisms are eukaryotic.
Every organism develops from a cell. This applies to organisms that were born as a result of both asexual and sexual reproduction methods. That is why the cell is considered a unit of growth and development of the organism.
Modern systematics distinguishes the following kingdoms of organisms: Bacteria, Fungi, Plants, Animals. The grounds for such a division are the methods of nutrition of these organisms and the structure of the cells.
bacterial cells have the following structures characteristic of them - a dense cell wall, one circular DNA molecule (nucleotide), ribosomes. These cells lack many of the organelles characteristic of eukaryotic plant, animal, and fungal cells. According to the mode of nutrition, bacteria are divided into autotrophs, chemotrophs and heterotrophs. Plant cells contain plastids characteristic only of them - chloroplasts, leukoplasts and chromoplasts; they are surrounded by a dense cell wall of cellulose, and also have vacuoles with cell sap. All green plants are autotrophic organisms.
Animal cells do not have dense cell walls. They are surrounded by a cell membrane through which the exchange of substances with the environment takes place.
Fungal cells are covered with a cell wall that differs in chemical composition from plant cell walls. It contains chitin, polysaccharides, proteins and fats as the main components. Glycogen is the reserve substance of fungal and animal cells.
EXAMPLES OF TASKS
Part A
A1. Which of the following is consistent with the cell theory
1) the cell is the elementary unit of heredity
2) the cell is the unit of reproduction
3) the cells of all organisms are different in their structure
4) the cells of all organisms have a different chemical composition
A2. Precellular life forms include:
1) yeast 3) bacteria
2) penicillium 4) viruses
A3. A plant cell differs from a fungal cell in structure:
1) nucleus 3) cell wall
2) mitochondria 4) ribosomes
A4. One cell consists of:
1) influenza virus and amoeba
2) mushroom mukor and cuckoo flax
3) planaria and volvox
4) euglena green and infusoria-shoe
A5. Prokaryotic cells have:
1) nucleus 3) Golgi apparatus
2) mitochondria 4) ribosomes
A6. The species affiliation of the cell is indicated by:
1) the shape of the nucleus
2) number of chromosomes
3) membrane structure
4) the primary structure of the protein
A7. The role of cell theory in science is
1) opening of the cell nucleus
2) cell opening
3) generalization of knowledge about the structure of organisms
4) discovery of metabolic mechanisms
Part B
IN 1. Select features that are characteristic only for plant cells
1) have mitochondria and ribosomes
2) cellulose cell wall
3) there are chloroplasts
4) reserve substance - glycogen
5) reserve substance - starch
6) the nucleus is surrounded by a double membrane
IN 2. Select the features that distinguish the kingdom of Bacteria from the rest of the kingdoms of the organic world.
1) heterotrophic mode of nutrition
2) autotrophic mode of nutrition
3) the presence of a nucleoid
4) lack of mitochondria
5) no core
6) the presence of ribosomes
VZ. Find a correspondence between the structural features of the cell and the kingdom to which these cells belong
Part WITH
C1. Give examples of eukaryotic cells that do not have a nucleus.
C2. Prove that the cell theory generalized a number of biological discoveries and predicted new discoveries.
2.3. The chemical organization of the cell. The relationship of the structure and functions of inorganic and organic substances (proteins, nucleic acids, carbohydrates, lipids, ATP) that make up the cell. Justification of the relationship of organisms based on the analysis of the chemical composition of their cells
The main terms and concepts tested in the examination paper: nitrogenous bases, enzyme active site, hydrophilicity, hydrophobicity, amino acids, ATP, proteins, biopolymers, denaturation, DNA, deoxyribose, complementarity, lipids, monomer, nucleotide, peptide bond, polymer, carbohydrates, ribose, RNA, enzymes, phospholipids.
2.3.1. Inorganic substances of the cell
The cell contains about 70 elements of the periodic system of elements of Mendeleev, and 24 of them are present in all types of cells. All elements present in the cell are divided, depending on their content in the cell, into groups:
macronutrients– H, O, N, C, Mg, Na, Ca, Fe, K, P, Cl, S;
trace elements– B, Ni, Cu, Co, Zn, Mb, etc.;
ultramicroelements– U, Ra, Au, Pb, Hg, Se, etc.
The cell contains molecules inorganic and organic connections.
Inorganic compounds of the cell - water and inorganic ions.
Water is the most important inorganic substance of the cell. All biochemical reactions take place in aqueous solutions. The water molecule has a non-linear spatial structure and has polarity. Hydrogen bonds are formed between individual water molecules, which determine the physical and chemical properties of water.
Physical properties of water: Since water molecules are polar, water has the property of dissolving polar molecules of other substances. Substances that are soluble in water are called hydrophilic. Substances that are insoluble in water are called hydrophobic.
Water has a high specific heat capacity. To break the numerous hydrogen bonds that exist between water molecules, it is necessary to absorb a large amount of energy. Remember how long it takes for a kettle to boil. This property of water ensures the maintenance of heat balance in the body.
It takes a lot of energy to evaporate water. The boiling point of water is higher than that of many other substances. This property of water protects the body from overheating.
Water can be in three states of aggregation - liquid, solid and gaseous.
Hydrogen bonds determine the viscosity of water and the adhesion of its molecules to the molecules of other substances. Due to the forces of adhesion of molecules, a film is created on the surface of the water, which has such a characteristic as surface tension.
When cooled, the movement of water molecules slows down. The number of hydrogen bonds between molecules becomes maximum. Water reaches its highest density at 4 Cº. As water freezes, it expands (requires room for hydrogen bonds to form) and its density decreases. That's why ice floats.
Biological functions of water. Water ensures the movement of substances in the cell and body, the absorption of substances and the excretion of metabolic products. In nature, water carries waste products to soils and water bodies.
Water is an active participant in metabolic reactions.
Water is involved in the formation of lubricating fluids and mucus, secrets and juices in the body. These fluids are found in the joints of vertebrates, in the pleural cavity, in the pericardial sac.
Water is part of the mucus, which facilitate the movement of substances through the intestines, create a humid environment on the mucous membranes of the respiratory tract. The secrets secreted by some glands and organs are also water-based: saliva, tears, bile, sperm, etc.
inorganic ions. The inorganic ions of the cell include: cations K +, Na +, Ca 2+, Mg 2+, NH 3 + and anions Cl -, NO 3 -, H 2 PO 4 -, NCO 3 -, HPO 4 2-.
The difference between the number of cations and anions (Na + , Ka + , Cl -) on the surface and inside the cell provides the emergence of an action potential, which underlies the nervous and muscle excitation.
anions phosphoric acids create phosphate buffer system, which maintains the pH of the intracellular environment of the body at the level of 6–9.
Carbonic acid and its anions create a bicarbonate buffer system and maintain the pH of the extracellular medium (blood plasma) at a level of 7–4.
Nitrogen compounds serve as a source of mineral nutrition, synthesis of proteins, nucleic acids. Phosphorus atoms are part of the nucleic acids, phospholipids, as well as the bones of vertebrates, the chitinous cover of arthropods. Calcium ions are part of the bone substance; they are also necessary for the implementation of muscle contraction, blood clotting.
EXAMPLES OF TASKS
A1. The polarity of water determines its ability
1) conduct heat 3) dissolve sodium chloride
2) absorb heat 4) dissolve glycerin
A2. Children with rickets should be given drugs containing
1) iron 2) potassium 3) calcium 4) zinc
A3. Conduction of a nerve impulse is provided by ions:
1) potassium and sodium 3) iron and copper
2) phosphorus and nitrogen 4) oxygen and chlorine
A4. Weak bonds between water molecules in its liquid phase are called:
1) covalent 3) hydrogen
2) hydrophobic 4) hydrophilic
A5. Hemoglobin contains
1) phosphorus 2) iron 3) sulfur 4) magnesium
A6. Choose a group of chemical elements that must be part of proteins
A7. Patients with hypothyroidism are given medications containing
Part B
IN 1. Select the functions of the water in the cage
1) energy 4) construction
2) enzymatic 5) lubricating
3) transport 6) thermoregulatory
IN 2. Select only the physical properties of water
1) the ability to dissociate
2) hydrolysis of salts
3) density
4) thermal conductivity
5) electrical conductivity
6) electron donation
Part WITH
C1. What physical properties of water determine its biological significance?
2.3.2. Organic matter of the cell. Carbohydrates, lipids
Carbohydrates. The general formula is Cn (H 2 O) n. Therefore, carbohydrates contain only three chemical elements in their composition.
Water-soluble carbohydrates.
Functions of soluble carbohydrates: transport, protective, signal, energy.
Monosaccharides: glucose- the main source of energy for cellular respiration. Fructose- an integral part of the nectar of flowers and fruit juices. Ribose and deoxyribose- structural elements of nucleotides, which are monomers of RNA and DNA.
Disaccharides: sucrose(glucose + fructose) is the main product of photosynthesis transported in plants. Lactose(glucose + galactose) - is part of the milk of mammals. Maltose(glucose + glucose) - energy source in germinating seeds.
Polymeric carbohydrates: starch, glycogen, cellulose, chitin. They are insoluble in water.
Functions of polymeric carbohydrates: structural, storage, energy, protective.
Starch consists of branched spiralized molecules that form reserve substances in plant tissues.
Cellulose- a polymer formed by glucose residues, consisting of several straight parallel chains connected by hydrogen bonds. This structure prevents the penetration of water and ensures the stability of the cellulose membranes of plant cells.
Chitin consists of amino derivatives of glucose. The main structural element of the integument of arthropods and the cell walls of fungi.
Glycogen is the storage material of an animal cell. Glycogen is even more branched than starch and highly soluble in water.
Lipids- esters of fatty acids and glycerol. Insoluble in water, but soluble in non-polar solvents. Present in all cells. Lipids are made up of hydrogen, oxygen and carbon atoms. Types of lipids: fats, waxes, phospholipids. Lipid functions: storage- fats are deposited in the stock in the tissues of vertebrates. Energy- half of the energy consumed by the cells of vertebrates at rest is formed as a result of fat oxidation. Fats are also used as a source of water. The energy effect from the breakdown of 1 g of fat is 39 kJ, which is twice the energy effect from the breakdown of 1 g of glucose or protein. Protective- the subcutaneous fat layer protects the body from mechanical damage. Structural - phospholipids are part of cell membranes. Thermal insulation- subcutaneous fat helps to keep warm. electrical insulating- myelin, secreted by Schwann cells (form the sheaths of nerve fibers), isolates some neurons, which many times accelerates the transmission of nerve impulses. Nutritious- Some lipid-like substances contribute to building muscle mass, maintaining body tone. Lubricating Waxes cover the skin, wool, feathers and protect them from water. The leaves of many plants are covered with a wax coating; wax is used in the construction of honeycombs. Hormonal- adrenal hormone - cortisone and sex hormones are lipid in nature.
TASK EXAMPLES
Part A
A1. A polysaccharide monomer can be:
1) amino acid
2) glucose
3) nucleotide
4) cellulose
A2. In animal cells, the storage carbohydrate is:
1) cellulose
2) starch
4) glycogen
A3. Most energy is released during splitting:
1) 10 g protein
2) 10 g glucose
3) 10 g fat
4) 10 g amino acid
A4. What function do lipids not perform?
1) energy
2) catalytic
3) insulating
4) storage
A5. Lipids can be dissolved in:
2) salt solution
3) hydrochloric acid
4) acetone
Part B
IN 1. Select the features of the structure of carbohydrates
1) consist of amino acid residues
2) consist of glucose residues
3) consist of hydrogen, carbon and oxygen atoms
4) some molecules have a branched structure
5) consist of fatty acid residues and glycerol
6) consist of nucleotides
IN 2. Select the functions that carbohydrates perform in the body
1) catalytic
2) transport
3) signal
4) building
5) protective
6) energy
VZ. Select the functions that lipids perform in the cell
1) structural
2) energy
3) storage
4) enzymatic
5) signal
6) transport
AT 4. Match the group of chemical compounds with their role in the cell
Part WITH
C1. Why does not glucose accumulate in the body, but starch and glycogen accumulate?
C2. Why does soap remove grease from hands?
2.3.3. Proteins, their structure and functions
Proteins are biological heteropolymers whose monomers are amino acids. Proteins are synthesized in living organisms and perform certain functions in them.
Proteins are made up of carbon, oxygen, hydrogen, nitrogen, and sometimes sulfur atoms. Protein monomers are amino acids - substances that have in their composition the invariable parts of the amino group NH 2 and the carboxyl group COOH and the variable part - the radical. Amino acids are distinguished from each other by radicals. Amino acids have the properties of an acid and a base (they are amphoteric), so they can combine with each other. Their number in one molecule can reach several hundred. The alternation of different amino acids in different sequences makes it possible to obtain a huge number of proteins that differ in structure and function.
There are 20 types of different amino acids found in proteins, some of which animals cannot synthesize. They get them from plants that can synthesize all the amino acids. It is to amino acids that proteins are broken down in the digestive tracts of animals. From these amino acids entering the cells of the body, its new proteins are built.
Structure of a protein molecule. The structure of a protein molecule is understood as its amino acid composition, the sequence of monomers and the degree of twisting of the molecule, which must fit in various sections and organelles of the cell, and not just one, but together with a huge number of other molecules.
The sequence of amino acids in a protein molecule forms its primary structure. It depends on the sequence of nucleotides in the region of the DNA molecule (gene) that encodes the given protein. Neighboring amino acids are linked by peptide bonds that arise between the carbon of the carboxyl group of one amino acid and the nitrogen of the amino group of another amino acid.
A long protein molecule folds and first takes the form of a spiral. This is how the secondary structure of the protein molecule arises. Between CO and NH - groups of amino acid residues, adjacent turns of the helix, hydrogen bonds arise that hold the chain.
A protein molecule of complex configuration in the form of a globule (ball) acquires a tertiary structure. The strength of this structure is provided by hydrophobic, hydrogen, ionic and disulfide S-S bonds.
Some proteins have a quaternary structure formed by several polypeptide chains (tertiary structures). The quaternary structure is also held by weak non-covalent bonds - ionic, hydrogen, hydrophobic. However, the strength of these bonds is low and the structure can be easily broken. When heated or treated with certain chemicals, the protein undergoes denaturation and loses its biological activity. Violation of the quaternary, tertiary and secondary structures is reversible. The destruction of the primary structure is irreversible.
In any cell, there are hundreds of protein molecules that perform various functions. In addition, proteins are species specific. This means that each species of organisms has proteins that are not found in other species. This creates serious difficulties when transplanting organs and tissues from one person to another, when grafting one type of plant onto another, etc.
Functions of proteins.
catalytic (enzymatic) - proteins accelerate all biochemical processes in the cell: the breakdown of nutrients in the digestive tract, participate in matrix synthesis reactions. Each enzyme speeds up one and only one reaction (both forward and backward). The rate of enzymatic reactions depends on the temperature of the medium, its pH level, as well as on the concentrations of the reactants and the concentration of the enzyme.
Transport- proteins provide active transport of ions through cell membranes, transport of oxygen and carbon dioxide, transport of fatty acids.
Protective- Antibodies provide immune defense of the body; fibrinogen and fibrin protect the body from blood loss.
Structural is one of the main functions of proteins. Proteins are part of cell membranes; keratin protein forms hair and nails; proteins collagen and elastin - cartilage and tendons.
Contractile Provided by contractile proteins actin and myosin.
Signal– protein molecules can receive signals and serve as their carriers in the body (hormones). It should be remembered that not all hormones are proteins.
Energy- during prolonged fasting, proteins can be used as an additional source of energy after carbohydrates and fats are used up.
EXAMPLES OF TASKS
Part A
A1. The sequence of amino acids in a protein molecule depends on:
1) gene structures
2) external environment
3) their random combination
4) their structures
A2. Man obtains essential amino acids through
1) their synthesis in cells
2) food intake
3) taking medication
4) taking vitamins
A3. As the temperature decreases, enzyme activity
1) noticeably increases
2) noticeably decreases
3) remains stable
4) changes periodically
A4. Involved in protecting the body from blood loss
1) hemoglobin
2) collagen
A5. In which of the following processes are proteins not involved?
1) metabolism
2) encoding of hereditary information
3) enzymatic catalysis
4) transport of substances
A6. Give an example of a peptide bond:
Part B
IN 1. Select functions specific to proteins
1) catalytic
2) hematopoietic
3) protective
4) transport
5) reflex
6) photosynthetic
IN 2. Establish a correspondence between the structure of a protein molecule and its features
Part WITH
C1. Why is food stored in the refrigerator?
C2. Why do cooked foods last longer?
SZ. Explain the concept of "specificity" of a protein, and what is the biological significance of specificity?
C4. Read the text, indicate the numbers of sentences in which errors were made and explain them 1) Most of the chemical reactions in the body are catalyzed by enzymes. 2) Each enzyme can catalyze many types of reactions. 3) The enzyme has an active center, the geometric shape of which changes depending on the substance with which the enzyme interacts. 4) An example of the action of an enzyme can be the decomposition of urea by urease. 5) Urea decomposes into carbon dioxide and ammonia, which smells like a cat litter box. 6) In one second, urease splits up to 30,000 urea molecules, under normal conditions, this would take about 3 million years.
2.3.4 Nucleic acids
Nucleic acids were discovered in 1868 by the Swiss scientist F. Miescher. In organisms, there are several types of nucleic acids that are found in various cell organelles - the nucleus, mitochondria, plastids. Nucleic acids include DNA, mRNA, tRNA, rRNA.
Deoxyribonucleic acid (DNA)- a linear polymer having the form of a double helix formed by a pair of antiparallel complementary (corresponding to each other in configuration) chains. The spatial structure of the DNA molecule was modeled by American scientists James Watson and Francis Crick in 1953.
The monomers of DNA are nucleotides . Each DNA nucleotide consists of a purine (A - adenine or G - guanine) or pyrimidine (T - thymine or C - cytosine) nitrogenous base, five-carbon sugar- deoxyribose and phosphate group.
Nucleotides in the DNA molecule face each other with nitrogenous bases and are combined in pairs in accordance with the rules of complementarity: thymine is located opposite adenine, and cytosine is opposite guanine. The A-T pair is connected by two hydrogen bonds, and the G-C pair by three. During replication (doubling) of DNA molecules, hydrogen bonds break and the chains diverge and a new DNA chain is synthesized on each of them. The backbone of DNA chains is formed by sugar-phosphate residues.
The sequence of nucleotides in a DNA molecule determines its specificity, as well as the specificity of the body proteins that are encoded by this sequence. These sequences are individual both for each type of organisms and for individual individuals.
Example: the DNA nucleotide sequence is given: CGA - TTA - CAA.
On the informational RNA (i-RNA), the chain GCU - AAU - GUU will be synthesized, as a result of which a chain of amino acids will be built: alanine - asparagine - valine.
When replacing nucleotides in one of the triplets or rearranging them, this triplet will encode another amino acid, and therefore the protein encoded by this gene will also change. (Using a school textbook, try to verify this.) Changes in the composition of nucleotides or their sequence are called mutations.
Ribonucleic acid (RNA)- a linear polymer consisting of a single chain of nucleotides. In RNA, a thymine nucleotide is replaced by a uracil nucleotide (U). Each RNA nucleotide contains a five-carbon sugar - ribose, one of the four nitrogenous bases and a phosphoric acid residue.
Types of RNA. matrix, or informational, RNA. Synthesized in the nucleus with the participation of the enzyme RNA polymerase. Complementary to the region of DNA where synthesis occurs. Its function is to remove information from DNA and transfer it to the site of protein synthesis - to ribosomes. It makes up 5% of the cell's RNA. Ribosomal RNA- is synthesized in the nucleolus and is part of the ribosomes. It makes up 85% of the cell's RNA. Transfer RNA(more than 40 types). Transports amino acids to the site of protein synthesis. It has the shape of a clover leaf and consists of 70-90 nucleotides.
Adenosine triphosphoric acid - ATP. ATP is a nucleotide consisting of a nitrogenous base - adenine, a ribose carbohydrate and three phosphoric acid residues, two of which store a large amount of energy. With the elimination of one residue of phosphoric acid, 40 kJ / mol of energy is released. Compare this figure with the figure indicating the amount of energy released by 1 g of glucose or fat. The ability to store such an amount of energy makes ATP its universal source. ATP synthesis occurs mainly in mitochondria.
EXAMPLES OF TASKS
Part A
A1. The monomers of DNA and RNA are
1) nitrogenous bases
2) phosphate groups
3) amino acids
4) nucleotides
A2. Messenger RNA function:
1) doubling information
2) removal of information from DNA
3) transport of amino acids to ribosomes
4) information storage
A3. Indicate the second DNA strand complementary to the first: ATT - GCC - TSH
1) UAA - TGG - AAC
2) TAA - CHG - AAC
3) UCC - GCC - ACG
4) TAA - UGG - UUTs
A4. Confirmation of the hypothesis that DNA is the genetic material of the cell is:
1) the number of nucleotides in a molecule
2) DNA personality
3) the ratio of nitrogenous bases (A \u003d T, G \u003d C)
4) ratio of DNA in gametes and somatic cells (1:2)
A5. The DNA molecule is capable of transmitting information due to:
1) nucleotide sequences
2) the number of nucleotides
3) the ability to self-doubling
4) spiralization of the molecule
A6. In which case is the composition of one of the RNA nucleotides correctly indicated?
1) thymine - ribose - phosphate
2) uracil - deoxyribose - phosphate
3) uracil - ribose - phosphate
4) adenine - deoxyribose - phosphate
Part B
IN 1. Select the features of the DNA molecule
1) Single chain molecule
2) Nucleotides - ATUC
3) Nucleotides - ATHC
4) Carbohydrate - ribose
5) Carbohydrate - deoxyribose
6) Capable of replication
IN 2. Select the functions characteristic of eukaryotic cell RNA molecules
1) distribution of hereditary information
2) transmission of hereditary information to the site of protein synthesis
3) transport of amino acids to the site of protein synthesis
4) initiation of DNA replication
5) formation of the ribosome structure
6) storage of hereditary information
Part WITH
C1. Establishing the structure of DNA made it possible to solve a number of problems. What, in your opinion, were these problems and how were they solved as a result of this discovery?
C2. Compare nucleic acids by composition and properties.
2.4. The structure of pro- and eukaryotic cells. The relationship of the structure and functions of the parts and organelles of the cell is the basis of its integrity
The main terms and concepts tested in the examination paper: Golgi apparatus, vacuole, cell membrane, cell theory, leukoplasts, mitochondria, cell organelles, plastids, prokaryotes, ribosomes, chloroplasts, chromoplasts, chromosomes, eukaryotes, nucleus.
Every cell is a system. This means that all its components are interconnected, interdependent and interact with each other. It also means that disruption of the activity of one of the elements of this system leads to changes and disruptions in the operation of the entire system. A set of cells forms tissues, various tissues form organs, and organs, interacting and performing a common function, form organ systems. This chain can be continued further, and you can do it yourself. The main thing to understand is that any system has a certain structure, level of complexity and is based on the interaction of the elements that make it up. Below are reference tables that compare the structure and function of prokaryotic and eukaryotic cells, and also analyze their structure and function. Carefully analyze these tables, because in the examination papers quite often questions are asked that require knowledge of this material.
2.4.1. Features of the structure of eukaryotic and prokaryotic cells. Comparative data
Comparative characteristics of eukaryotic and prokaryotic cells.
The structure of eukaryotic cells.
Functions of eukaryotic cells . Cells of unicellular organisms carry out all the functions characteristic of living organisms - metabolism, growth, development, reproduction; capable of adaptation.
The cells of multicellular organisms are differentiated in structure, depending on the functions they perform. Epithelial, muscle, nervous, connective tissues are formed from specialized cells.
EXAMPLES OF TASKS
Part A
A1. Prokaryotic organisms include
1) bacillus
4) volvox
A2. The cell membrane performs the function
1) protein synthesis
2) transmission of hereditary information
3) photosynthesis
4) phagocytosis and pinocytosis
A3. Indicate the point at which the structure of the named cell coincides with its function
1) neuron - contraction
2) leukocyte - impulse conduction
3) erythrocyte - gas transport
4) osteocyte - phagocytosis
A4. Cellular energy is produced in
1) ribosomes
2) mitochondria
4) Golgi apparatus
A5. Eliminate the unnecessary concept from the proposed list
1) lamblia
2) plasmodium
3) infusoria
4) chlamydomonas
A6. Eliminate the unnecessary concept from the proposed list
1) ribosomes
2) mitochondria
3) chloroplasts
4) starch grains
A7. The chromosomes of a cell perform the function
1) protein biosynthesis
2) storage of hereditary information
3) formation of lysosomes
4) regulation of metabolism
Part B
IN 1. Select from the proposed list the functions of chloroplasts
1) the formation of lysosomes
2) glucose synthesis
4) ATP synthesis
3) RNA synthesis
5) release of oxygen
6) cellular respiration
IN 2. Choose the structural features of mitochondria
1) Surrounded by a double membrane
3) there are cristae
4) the outer membrane is folded
5) surrounded by a single membrane
6) the inner membrane is rich in enzymes
VZ. Match the organelle with its function
AT 4. Fill in the table, marking with signs "+" or "-" the presence of these structures in pro- and eukaryotic cells
Part WITH
C1. Prove that the cell is an integral biological, open system.
2.5. Metabolism: energy and plastic metabolism, their relationship. Enzymes, their chemical nature, role in metabolism. Stages of energy metabolism. Fermentation and respiration. Photosynthesis, its significance, cosmic role. Phases of photosynthesis. Light and dark reactions of photosynthesis, their relationship. Chemosynthesis. The role of chemosynthetic bacteria on Earth
Terms tested in the examination paper: autotrophic organisms, anabolism, anaerobic glycolysis, assimilation, aerobic glycolysis, biological oxidation, fermentation, dissimilation, biosynthesis, heterotrophic organisms, respiration, catabolism, oxygen stage, metabolism, plastic metabolism, preparatory stage, photosynthesis light phase, photosynthesis dark phase, water photolysis , photosynthesis, energy metabolism.
2.5.1. Energy and plastic metabolism, their relationship
Metabolism (metabolism) is a set of interrelated processes of synthesis and breakdown of chemicals occurring in the body. Biologists divide it into plastic ( anabolism) and energy exchanges ( catabolism) that are related. All synthetic processes require substances and energy supplied by fission processes. The processes of splitting are catalyzed by enzymes synthesized in the course of plastic metabolism, using the products and energy of energy metabolism.
For individual processes occurring in organisms, the following terms are used:
Anabolism (assimilation) - the synthesis of more complex monomers from simpler ones with the absorption and accumulation of energy in the form of chemical bonds in the synthesized substances.
catabolism (dissimilation) - the breakdown of more complex monomers into simpler ones with the release of energy and its storage in the form of macroergic bonds of ATP.
Living beings use light and chemical energy for their life activity. Green plants - autotrophs , - synthesize organic compounds in the process of photosynthesis, using the energy of sunlight. Their source of carbon is carbon dioxide. Many autotrophic prokaryotes obtain energy in the process chemosynthesis– oxidation of inorganic compounds. For them, compounds of sulfur, nitrogen, carbon can be an energy source. Heterotrophs use organic sources of carbon, i.e., feed on ready-made organic substances. Among plants, there may be those that feed in a mixed way ( mixotrophically) - sundew, venus flytrap or even heterotrophically - rafflesia. Of the representatives of unicellular animals, green euglena are considered mixotrophs.
Enzymes, their chemical nature, role in metabolism. Enzymes are always specific proteins - catalysts. The term "specific" means that the object in relation to which this term is used has unique features, properties, characteristics. Each enzyme has such characteristics because, as a rule, it catalyzes a certain type of reaction. Not a single biochemical reaction in the body occurs without the participation of enzymes. The specific features of the enzyme molecule are explained by its structure and properties. The enzyme molecule has an active center, the spatial configuration of which corresponds to the spatial configuration of the substances with which the enzyme interacts. Having recognized its substrate, the enzyme interacts with it and accelerates its transformation.
Enzymes catalyze all biochemical reactions. Without their participation, the rate of these reactions would decrease hundreds of thousands of times. Examples include reactions such as the participation of RNA polymerase in the synthesis of mRNA on DNA, the action of urease on urea, the role of ATP synthetase in the synthesis of ATP, and others. Note that the names of many enzymes end in "aza".
The activity of enzymes depends on the temperature, the acidity of the medium, the amount of the substrate with which it interacts. As the temperature rises, enzyme activity increases. However, this happens up to certain limits, since at sufficiently high temperatures the protein is denatured. The environment in which enzymes can function is different for each group. There are enzymes that are active in an acidic or slightly acidic environment, or in an alkaline or slightly alkaline environment. In an acidic environment, gastric juice enzymes are active in mammals. In a weakly alkaline environment, intestinal juice enzymes are active. The digestive enzyme of the pancreas is active in an alkaline environment. Most enzymes are active in a neutral environment.
2.5.2. Energy metabolism in the cell (dissimilation)
energy exchange- This is a set of chemical reactions of the gradual decomposition of organic compounds, accompanied by the release of energy, part of which is spent on the synthesis of ATP. The processes of splitting organic compounds in aerobic organisms occur in three stages, each of which is accompanied by several enzymatic reactions.
First stage - preparatory . In the gastrointestinal tract of multicellular organisms, it is carried out by digestive enzymes. In unicellular organisms, they are enzymes of lysosomes. The first step is the breakdown of proteins. to amino acids, fats to glycerol and fatty acids, polysaccharides to monosaccharides, nucleic acids to nucleotides. This process is called digestion.
Second phase - anoxic (glycolysis ). Its biological meaning lies in the beginning of the gradual breakdown and oxidation of glucose with the accumulation of energy in the form of 2 ATP molecules. Glycolysis occurs in the cytoplasm of cells. It consists of several successive reactions of converting a glucose molecule into two molecules of pyruvic acid (pyruvate) and two ATP molecules, in the form of which part of the energy released during glycolysis is stored: C 6 H 12 O 6 + 2ADP + 2F → 2C 3 H 4 O 3 + 2ATP. The rest of the energy is dissipated as heat.
In yeast and plant cells ( with a lack of oxygen) pyruvate breaks down into ethyl alcohol and carbon dioxide. This process is called alcoholic fermentation .
The energy stored in glycolysis is too small for organisms that use oxygen for their respiration. That is why in the muscles of animals, including humans, under heavy loads and lack of oxygen, lactic acid (C 3 H 6 O 3) is formed, which accumulates in the form of lactate. There is pain in the muscles. In untrained people, this happens faster than in trained people.
Third stage - oxygen , consisting of two consecutive processes - the Krebs cycle, named after the Nobel laureate Hans Krebs, and oxidative phosphorylation. Its meaning lies in the fact that during oxygen respiration, pyruvate is oxidized to the final products - carbon dioxide and water, and the energy released during oxidation is stored in the form of 36 ATP molecules. (34 molecules in the Krebs cycle and 2 molecules in the course of oxidative phosphorylation). This energy of decomposition of organic compounds provides the reactions of their synthesis in plastic exchange. The oxygen stage arose after the accumulation of a sufficient amount of molecular oxygen in the atmosphere and the appearance of aerobic organisms.
Oxidative phosphorylation or cellular respiration occurs on the inner membranes of mitochondria, in which electron carrier molecules are embedded. During this stage, most of the metabolic energy is released. Carrier molecules transport electrons to molecular oxygen. Part of the energy is dissipated in the form of heat, and part is spent on the formation of ATP.
The total reaction of energy metabolism:
C 6 H 12 O 6 + 6O 2 → 6CO 2 + 6H 2 O + 38ATP.
EXAMPLES OF TASKS
A1. The way carnivores eat is called
1) autotrophic
2) mixotrophic
3) heterotrophic
4) chemotrophic
A2. The set of metabolic reactions is called:
1) anabolism
2) assimilation
3) dissimilation
4) metabolism
A3. At the preparatory stage of energy metabolism, the formation of:
1) 2 molecules of ATP and glucose
2) 36 molecules of ATP and lactic acid
3) amino acids, glucose, fatty acids
4) acetic acid and alcohol
A4. Substances that catalyze biochemical reactions in the body are:
2) nucleic acids
4) carbohydrates
A5. The process of ATP synthesis during oxidative phosphorylation occurs in:
1) cytoplasm
2) ribosomes
3) mitochondria
4) Golgi apparatus
A6. The energy of ATP stored in the process of energy metabolism is partially used for reactions:
1) preparatory stage
2) glycolysis
3) oxygen stage
4) synthesis of organic compounds
A7. The products of glycolysis are:
1) glucose and ATP
2) carbon dioxide and water
3) pyruvic acid and ATP
4) proteins, fats, carbohydrates
Part B
IN 1. Select the events that occur at the preparatory stage of human energy metabolism
1) proteins are broken down into amino acids
2) glucose is broken down into carbon dioxide and water
3) 2 ATP molecules are synthesized
4) glycogen is broken down to glucose
5) lactic acid is formed
6) lipids are broken down to glycerol and fatty acids
IN 2. Match the processes that occur during energy exchange with the stages at which they occur
VZ. Determine the sequence of transformations of a piece of raw potato in the process of energy metabolism in the body of a pig:
A) the formation of pyruvate
B) the formation of glucose
B) absorption of glucose into the blood
D) the formation of carbon dioxide and water
E) oxidative phosphorylation and the formation of H 2 O
E) the Krebs cycle and the formation of CO 2
Part C
C1. Explain the reasons for the fatigue of marathon athletes at distances, and how is it overcome?
2.5.3. Photosynthesis and chemosynthesis
All living beings need food and nutrients. When eating, they use the energy stored primarily in organic compounds - proteins, fats, carbohydrates. Heterotrophic organisms, as already mentioned, use food of plant and animal origin, which already contains organic compounds. Plants create organic matter through photosynthesis. Research in the field of photosynthesis began in 1630 with the experiments of the Dutchman van Helmont. He proved that plants do not get organic substances from the soil, but create them on their own. Joseph Priestley in 1771 proved the "correction" of the air by plants. Placed under a glass cap, they absorbed carbon dioxide released by a smoldering torch. Research has continued and it is now established that photosynthesis - this is the process of formation of organic compounds from carbon dioxide (CO 2) and water using light energy and taking place in the chloroplasts of green plants and the green pigments of some photosynthetic bacteria.
Chloroplasts and folds of the cytoplasmic membrane of prokaryotes contain a green pigment - chlorophyll. The chlorophyll molecule is able to be excited by the action of sunlight and donate its electrons and move them to higher energy levels. This process can be compared to a ball tossed up. As the ball rises, it stores up potential energy; falling, he loses it. Electrons do not fall back, but are picked up by electron carriers (NADP + - nicotinamide diphosphate). At the same time, the energy accumulated by them earlier is partially spent on the formation of ATP. Continuing the comparison with a tossed ball, we can say that the ball, falling, heats up the surrounding space, and part of the energy of the incident electrons is stored in the form of ATP. The process of photosynthesis is divided into reactions caused by light and reactions associated with carbon fixation. They are called light and dark phases.
"Light Phase" is the stage at which the light energy absorbed by chlorophyll is converted into electrochemical energy in the electron transport chain. Carried out in the light, in gran membranes with the participation of carrier proteins and ATP synthetase.
Light-induced reactions occur on the photosynthetic membranes of the gran chloroplasts:
1) excitation of chlorophyll electrons by light quanta and their transition to a higher energy level;
2) reduction of electron acceptors - NADP + to NADP H
2H + + 4e - + NADP + → NADP H;
3) photolysis of water, occurring with the participation of light quanta: 2H 2 O → 4H + + 4e - + O 2.
This process takes place within thylakoids- folds of the inner membrane of chloroplasts. Thylakoids form grana - stacks of membranes.
Since the examination papers do not ask about the mechanisms of photosynthesis, but about the results of this process, we will move on to them.
The results of light reactions are: photolysis of water with the formation of free oxygen, ATP synthesis, reduction of NADP + to NADP H. Thus, light is needed only for the synthesis of ATP and NADP-H.
"Dark Phase"- the process of converting CO 2 into glucose in the stroma (the space between the grana) of chloroplasts using the energy of ATP and NADP H.
The result of dark reactions is the conversion of carbon dioxide into glucose, and then into starch. In addition to glucose molecules in the stroma, amino acids, nucleotides, and alcohols are formed.
The overall photosynthesis equation is -
The Importance of Photosynthesis. In the process of photosynthesis, free oxygen is formed, which is necessary for the respiration of organisms:
oxygen formed a protective ozone screen that protects organisms from the harmful effects of ultraviolet radiation;
photosynthesis ensures the production of initial organic substances, and therefore food for all living beings;
photosynthesis helps to reduce the concentration of carbon dioxide in the atmosphere.
Chemosynthesis - the formation of organic compounds from inorganic ones due to the energy of redox reactions of nitrogen, iron, sulfur compounds. There are several types of chemosynthetic reactions:
1) oxidation of ammonia to nitrous and nitric acid by nitrifying bacteria:
NH 3 → HNQ 2 → HNO 3 + Q;
2) the conversion of ferrous iron to trivalent iron bacteria:
Fe 2+ → Fe 3+ + Q;
3) oxidation of hydrogen sulfide to sulfur or sulfuric acid by sulfur bacteria
H 2 S + O 2 \u003d 2H 2 O + 2S + Q,
H 2 S + O 2 \u003d 2H 2 SO 4 + Q.
The released energy is used for the synthesis of organic substances.
The role of chemosynthesis. Bacteria - chemosynthetics, destroy rocks, purify wastewater, participate in the formation of minerals.
EXAMPLES OF TASKS
A1. Photosynthesis is a process that takes place in green plants. It is associated with:
1) the breakdown of organic substances to inorganic
2) the creation of organic substances from inorganic
3) chemical conversion of glucose into starch
4) the formation of cellulose
A2. The starting material for photosynthesis is
1) proteins and carbohydrates
2) carbon dioxide and water
3) oxygen and ATP
4) glucose and oxygen
A3. The light phase of photosynthesis occurs
1) in the grana of chloroplasts
2) in leukoplasts
3) in the stroma of chloroplasts
4) in mitochondria
A4. The energy of excited electrons in the light stage is used to:
1) ATP synthesis
2) glucose synthesis
3) protein synthesis
4) breakdown of carbohydrates
A5. As a result of photosynthesis, chloroplasts produce:
1) carbon dioxide and oxygen
2) glucose, ATP and oxygen
3) proteins, fats, carbohydrates
4) carbon dioxide, ATP and water
A6. Chemotrophic organisms are
1) causative agents of tuberculosis
2) lactic acid bacteria
3) sulfur bacteria
Part B
IN 1. Select the processes occurring in the light phase of photosynthesis
1) photolysis of water
2) the formation of glucose
3) synthesis of ATP and NADP H
4) use of CO 2
5) formation of free oxygen
6) use of ATP energy
IN 2. Choose the substances involved in the process of photosynthesis
1) cellulose
2) glycogen
3) chlorophyll
4) carbon dioxide
6) nucleic acids
Part WITH
C1. What conditions are necessary for the process of photosynthesis to start?
C2. How does the structure of the leaf provide its photosynthetic functions?
2.6. Biosynthesis of proteins and nucleic acids. Matrix nature of biosynthetic reactions. Genetic information in a cell. Genes, genetic code and its properties
Terms and concepts tested in the examination paper: anticodon, biosynthesis, gene, genetic information, genetic code, codon, matrix synthesis, polysome, transcription, translation.
Genes, genetic code and its properties. More than 6 billion people live on Earth. Except for 25-30 million pairs of identical twins, then genetically all people are different. This means that each of them is unique, has unique hereditary characteristics, character traits, abilities, temperament and many other qualities. What determines such differences between people? Of course, the differences in their genotypes, i.e., the sets of genes of a given organism. Each person is unique, just as the genotype of an individual animal or plant is unique. But the genetic characteristics of a given person are embodied in proteins synthesized in his body. Consequently, the structure of the protein of one person differs, although quite a bit, from the protein of another person. That's why the problem of organ transplants arises, that's why allergic reactions to food, insect bites, plant pollen, etc. occur. This does not mean that people do not have exactly the same proteins. Proteins that perform the same functions may be the same or very slightly differ by one or two amino acids from each other. But there are no people on Earth (with the exception of identical twins) in whom all proteins would be the same.
Information about the primary structure of a protein is encoded as a sequence of nucleotides in a section of a DNA molecule - a gene. Gene is a unit of hereditary information of an organism. Each DNA molecule contains many genes. The totality of all the genes of an organism makes up its genotype.
Encoding of hereditary information occurs with the help of the genetic code. The code is similar to the well-known Morse code, which encodes information with dots and dashes. Morse code is universal for all radio operators, and the differences are only in the translation of signals into different languages. Genetic code is also universal for all organisms and differs only in the alternation of nucleotides that form genes and code for proteins of specific organisms. So what is the genetic code? Initially, it consists of triplets (triplets) of DNA nucleotides, combined in different sequences. For example, AAT, HCA, ACH, THC, etc. Each triplet of nucleotides encodes a specific amino acid that will be built into the polypeptide chain. For example, the CHT triplet codes for the amino acid alanine, and the AAG triplet codes for the amino acid phenylalanine. There are 20 amino acids, and there are 64 possibilities for combinations of four nucleotides in groups of three. Therefore, four nucleotides is enough to encode 20 amino acids. That is why one amino acid can be encoded by several triplets. Some of the triplets do not encode amino acids at all, but start or stop protein biosynthesis. Actually the code is considered sequence of nucleotides in an i-RNA molecule, because it removes information from DNA (the process of transcription) and translates it into a sequence of amino acids in the molecules of synthesized proteins (the process of translation). The composition and RNA include nucleotides of ACGU. Triplets of nucleotides and RNA are called codons . The already given examples of DNA triplets on mRNA will look like this: the CHT triplet on mRNA will become the HCA triplet, and the DNA triplet AAG will become the UUC triplet. It is the codons of i-RNA that reflect the genetic code in the record. So, the genetic code is triplet, universal for all organisms on earth, degenerate (each amino acid is encrypted by more than one codon). Between the genes there are punctuation marks - these are triplets, which are called stop codons. They signal the end of the synthesis of one polypeptide chain. There are tables of the genetic code that you need to be able to use to decipher the codons of i-RNA and build chains of protein molecules.
Protein biosynthesis- this is one of the types of plastic exchange, during which the hereditary information encoded in the DNA genes is realized in a certain sequence of amino acids in protein molecules. Genetic information taken from DNA and translated into the code of an i-RNA molecule must be realized, i.e., manifest itself in the characteristics of a particular organism. These signs are determined by proteins. Protein biosynthesis occurs on ribosomes in the cytoplasm. This is where messenger RNA comes from the nucleus of the cell. If the synthesis of mRNA on a DNA molecule is called transcription, then protein synthesis on ribosomes is called broadcast- translation of the language of the genetic code into the language of the sequence of amino acids in the protein molecule. Amino acids are delivered to ribosomes by transfer RNAs. These RNAs are shaped like a cloverleaf. At the end of the molecule there is a platform for attaching an amino acid, and at the top there is a triplet of nucleotides that is complementary to a specific triplet - a codon on mRNA. This triplet is called an anticodon. After all, he deciphers the i-RNA code. There is always as much tRNA in a cell as there are codons encoding amino acids.
The ribosome moves along the mRNA, shifting three nucleotides when a new amino acid arrives, freeing them for a new anticodon. Amino acids delivered to ribosomes are oriented with respect to each other so that the carboxyl group of one amino acid is next to the amino group of another amino acid. As a result, a peptide bond is formed between them. Gradually, a polypeptide molecule is formed.
Protein synthesis continues until one of the three stop codons - UAA, UAG, or UGA - is found on the ribosome.
After that, the polypeptide leaves the ribosome and goes to the cytoplasm. One mRNA molecule contains several ribosomes that form polysome. It is on polysomes that the simultaneous synthesis of several identical polypeptide chains.
Each step of biosynthesis is catalyzed by the corresponding enzyme and provided with the energy of ATP.
Biosynthesis occurs in cells at a tremendous speed. In the body of higher animals, up to 60 thousand peptide bonds are formed in one minute.
Matrix synthesis reactions. Matrix synthesis reactions include replication DNA, i-RNA synthesis on DNA ( transcription), and protein synthesis on mRNA ( broadcast), as well as the synthesis of RNA or DNA on the RNA of viruses.
DNA replication. The structure of the DNA molecule, established by J. Watson and F. Crick in 1953, met the requirements that were imposed on the storage molecule and transmitter of hereditary information. The DNA molecule consists of two complementary strands. These chains are held together by weak hydrogen bonds that can be broken by enzymes.
The molecule is capable of self-doubling (replication), and on each old half of the molecule a new half of it is synthesized. In addition, an mRNA molecule can be synthesized on a DNA molecule, which then transfers the information received from DNA to the site of protein synthesis. Information transfer and protein synthesis follow a matrix principle, comparable to the work of a printing press in a printing house. Information from DNA is copied over and over again. If errors occur during copying, they will be repeated in all subsequent copies. True, some errors in copying information by a DNA molecule can be corrected. This debugging process is called reparations. The first of the reactions in the process of information transfer is the replication of the DNA molecule and the synthesis of new DNA strands.
replication- This is the process of self-duplication of the DNA molecule, carried out under the control of enzymes. On each of the DNA strands formed after the breaking of hydrogen bonds, with the participation of the enzyme DNA polymerase, a daughter strand of DNA is synthesized. The material for synthesis is free nucleotides present in the cytoplasm of cells.
The biological meaning of replication lies in the exact transfer of hereditary information from the parent molecule to the daughter ones, which normally occurs during the division of somatic cells.
Transcription is the process of removing information from a DNA molecule synthesized on it by an mRNA molecule. Messenger RNA consists of a single strand and is synthesized on DNA in accordance with the rule of complementarity. As in any other biochemical reaction, an enzyme is involved in this synthesis. It activates the beginning and end of the synthesis of the mRNA molecule. The finished mRNA molecule enters the cytoplasm on the ribosomes, where the synthesis of polypeptide chains takes place. The process of translating the information contained in the nucleotide sequence of an i-RNA into the sequence of amino acids in a polypeptide is called broadcast .
EXAMPLES OF TASKS
Part A
A1. Which of the statements is incorrect?
1) the genetic code is universal
2) the genetic code is degenerate
3) the genetic code is individual
4) the genetic code is triplet
A2. One DNA triplet encodes:
1) the sequence of amino acids in a protein
2) one sign of the organism
3) one amino acid
4) several amino acids
A3. "Punctuation marks" of the genetic code
1) start protein synthesis
2) stop protein synthesis
3) encode certain proteins
4) encode a group of amino acids
A4. If in a frog the amino acid VALIN is encoded by the GUU triplet, then in a dog this amino acid can be encoded by triplets (see table):
1) GUA and GUG 3) CUC and CUA
2) UTC and UCA 4) UAG and UGA
A5. Protein synthesis is completed at the moment
1) codon recognition by anticodon
2) receipt of i-RNA on ribosomes
3) the appearance of a "punctuation mark" on the ribosome
4) amino acid attachment to tRNA
A6. Specify a pair of cells in which one person contains different genetic information?
1) liver and stomach cells
2) neuron and leukocyte
3) muscle and bone cells
4) tongue cell and egg
A7. The function of i-RNA in the process of biosynthesis
1) storage of hereditary information
2) transport of amino acids to ribosomes
3) transfer of information to ribosomes
4) acceleration of the biosynthesis process
A8. The tRNA anticodon consists of UCG nucleotides. Which DNA triplet is complementary to it?
Part B
IN 1. Establish a correspondence between the characteristics of the process and its name
Part C
C1. Specify the sequence of amino acids in a protein molecule encoded by the following codon sequence: UUA - AYU - HCU - HGA
C2. List all steps of protein biosynthesis.
2.7. The cell is the genetic unit of living things. Chromosomes, their structure (shape and size) and functions. The number of chromosomes and their species constancy. Features of somatic and germ cells. Cell life cycle: interphase and mitosis. Mitosis is the division of somatic cells. Meiosis. Phases of mitosis and meiosis. The development of germ cells in plants and animals. Similarities and differences between mitosis and meiosis, their significance. Cell division is the basis for the growth, development and reproduction of organisms. The role of meiosis in ensuring the constancy of the number of chromosomes in generations
Terms and concepts tested in the examination paper: anaphase, gamete, gametogenesis, cell division, cell life cycle, zygote, interphase, conjugation, crossing over, meiosis, metaphase, oogenesis, testis, spermatozoon, spore, telophase, ovary, structure and functions of chromosomes.
Chromosomes - cell structures that store and transmit hereditary information. A chromosome is made up of DNA and protein. A complex of proteins associated with DNA forms chromatin. Proteins play an important role in the packaging of DNA molecules in the nucleus. The structure of the chromosome is best seen in the metaphase of mitosis. It is a rod-shaped structure and consists of two sister chromatids held by the centromere in the area primary constriction. The diploid set of chromosomes in an organism is called karyotype . Under a microscope, you can see that the chromosomes have transverse stripes that alternate in different chromosomes in different ways. Pairs of chromosomes are recognized, taking into account the distribution of light and dark stripes (alternation of AT and GC - pairs). The chromosomes of representatives of different species have transverse striation. In related species, for example, in humans and chimpanzees, a similar pattern of alternation of bands in the chromosomes.
Each species of organisms has a constant number, shape and composition of chromosomes. The human karyotype has 46 chromosomes - 44 autosomes and 2 sex chromosomes. Males are heterogametic (sex chromosomes XY) and females are homogametic (sex chromosomes XX). The Y chromosome differs from the X chromosome in the absence of some alleles. For example, there is no allele for blood clotting on the Y chromosome. As a result, hemophilia usually only affects boys. Chromosomes of one pair are called homologous. Homologous chromosomes in the same loci (locations) carry allelic genes.
Cell life cycle. Interphase. Mitosis. Cell life cycle- this is the period of her life from division to division. Cells reproduce by doubling their contents and then dividing in half. Cell division underlies the growth, development and regeneration of tissues of a multicellular organism. cell cycle subdivided into interphase accompanied by exact copying and distribution of genetic material and mitosis- proper cell division after doubling of other cellular components. The duration of cell cycles in different species, in different tissues and at different stages varies widely from one hour (in an embryo) to a year (in adult liver cells).
Interphase is the period between two divisions. During this period, the cell prepares for division. The amount of DNA in the chromosomes doubles. The number of other organelles doubles, proteins are synthesized, and the most active of them are those that form the spindle of division, cell growth occurs.
By the end of interphase, each chromosome consists of two chromatids, which will become independent chromosomes during mitosis.
Mitosis is a form of division of the cell nucleus. Therefore, it occurs only in eukaryotic cells. As a result of mitosis, each of the resulting daughter nuclei receives the same set of genes that the parent cell had. Both diploid and haploid nuclei can enter mitosis. During mitosis, nuclei of the same ploidy are obtained as the original. Mitosis consists of several successive phases.
Prophase. Doubled centrioles diverge to different poles of the cell. Microtubules extend from them to the centromeres of chromosomes, forming a spindle of division. Chromosomes are thickened and each chromosome consists of two chromatids.
metaphase. In this phase, chromosomes consisting of two chromatids are clearly visible. They line up along the equator of the cell, forming a metaphase plate.
Anaphase. Chromatids diverge towards the poles of the cell at the same speed. Microtubules shorten.
Telophase. Daughter chromatids approach the poles of the cell. Microtubules disappear. Chromosomes despiralize and revert to filamentous form. The nuclear envelope, nucleolus, and ribosomes are formed.
cytokinesis- the process of division of the cytoplasm. The cell membrane in the central part of the cell is pulled inward. A fission furrow is formed, as it deepens, the cell bifurcates.
As a result of mitosis, two new nuclei are formed with identical sets of chromosomes, exactly copying the genetic information of the parent nucleus.
In tumor cells, the course of mitosis is disturbed.
EXAMPLES OF TASKS
Part A
A1. Chromosomes are made up of
1) DNA and protein 3) DNA and RNA
2) RNA and protein 4) DNA and ATP
A2. How many chromosomes does a human liver cell contain?
1) 46 2) 23 3) 92 4) 66
A3. How many strands of DNA does a duplicated chromosome have?
1) one 2) two 3) four 4) eight
A4. If a human zygote contains 46 chromosomes, how many chromosomes are there in a human egg?
1) 46 2) 23 3) 92 4) 22
A5. What is the biological meaning of chromosome doubling in the interphase of mitosis?
1) In the process of doubling, hereditary information changes
2) Doubled chromosomes are better visible
3) As a result of chromosome doubling, the hereditary information of new cells remains unchanged
4) As a result of chromosome doubling, new cells contain twice as much information
A6. In which phase of mitosis does the chromatid move to the poles of the cell? V:
1) prophase 3) anaphase
2) metaphase 4) telophase
A7. Specify the processes occurring in the interphase
1) divergence of chromosomes to the poles of the cell
2) protein synthesis, DNA replication, cell growth
3) the formation of new nuclei, cell organelles
4) despiralization of chromosomes, formation of a fission spindle
A8. Mitosis results in
1) genetic diversity of species
2) the formation of gametes
3) chromosome crossing
4) germination of moss spores
A9. How many chromatids does each chromosome have before it is duplicated?
1) 2 2) 4 3) 1 4) 3
A10. As a result of mitosis,
1) zygote in sphagnum
2) spermatozoa in a fly
3) oak buds
4) sunflower eggs
Part B
IN 1. Select the processes occurring in the interphase of mitosis
1) protein synthesis
2) a decrease in the amount of DNA
3) cell growth
4) duplication of chromosomes
5) divergence of chromosomes
6) nuclear fission
IN 2. Specify the processes that are based on mitosis
1) mutations 4) sperm formation
2) growth 5) tissue regeneration
3) crushing of the zygote 6) fertilization
VZ. Set the correct sequence of phases of the cell life cycle
A) anaphase B) telophase E) metaphase
B) interphase D) prophase E) cytokinesis
Part WITH
C1. What is common between the processes of tissue regeneration, the growth of the organism, and the fragmentation of the zygote?
C2. What is the biological meaning of chromosome doubling and the amount of DNA in interphase?
Meiosis. Meiosis is the process of division of cell nuclei, leading to a halving of the number of chromosomes and the formation of gametes. As a result of meiosis, four haploid cells (n) are formed from one diploid cell (2n).
Meiosis consists of two successive divisions preceded by a single DNA replication in interphase.
The main events of the prophase of the first division of meiosis are as follows:
- homologous chromosomes are combined along the entire length or, as they say, are conjugated. During conjugation, chromosome pairs are formed - bivalents;
- as a result, complexes are formed consisting of two homologous chromosomes or four chromatids (think about what it's for?);
- at the end of prophase, a crossing over (crossover) occurs between homologous chromosomes: chromosomes exchange homologous regions with each other. It is crossing over that ensures the diversity of genetic information received by children from their parents.
In metaphase I chromosomes line up along the equator of the spindle. The centromeres are facing the poles.
Anaphase I - the spindle threads contract, homologous chromosomes, consisting of two chromatids, diverge to the poles of the cell, where haploid sets of chromosomes are formed (2 sets per cell). At this stage, chromosomal recombinations occur, which increase the degree of variability of the offspring.
Telophase I - cells are formed with haploid set of chromosomes and double the amount of DNA. The nuclear envelope is formed. Each cell contains 2 sister chromatids connected by a centromere.
The second division of meiosis consists of prophase II, metaphase II, anaphase II, telophase II, and cytokinesis.
The biological significance of meiosis consists in the formation of cells involved in sexual reproduction, in maintaining the genetic constancy of species, as well as in sporulation in higher plants. Spores of mosses, ferns and some other groups of plants are formed by meiosis. Meiosis is the basis of combinative variability in organisms. Violations of meiosis in humans can lead to pathologies such as Down's disease, idiocy, etc.
The development of sex cells.
The process of formation of germ cells is called gametogenesis. In multicellular organisms, spermatogenesis is distinguished - the formation of male germ cells and oogenesis - the formation of female germ cells. Consider the gametogenesis that occurs in the sex glands of animals - the testes and ovaries.
spermatogenesis- the process of transformation of diploid precursors of germ cells - spermatogonia into spermatozoa.
1. Spermatogonia are divided into two daughter cells - spermatocytes of the first order.
2. First-order spermatocytes are divided by meiosis (1st division) into two daughter cells - second-order spermatocytes.
3. Spermatocytes of the second order begin the second meiotic division, as a result of which 4 haploid spermatids are formed.
4. After differentiation, spermatids turn into mature spermatozoa.
The spermatozoon consists of a head, neck and tail. It is mobile and due to this the probability of meeting it with gametes increases.
In mosses and ferns, spermatozoa develop in antheridia; in angiosperms, they are formed in pollen tubes.
Ovogenesis- the formation of eggs in females. In animals, it occurs in the ovaries. In the breeding zone are ovogonia - primary germ cells that reproduce by mitosis.
From the ogonium after the first meiotic division, oocytes of the first order are formed.
After the second meiotic division, second-order oocytes are formed, from which one egg and three directional bodies are formed, which then die. The eggs are immobile, have a spherical shape. They are larger than other cells and contain a supply of nutrients for the development of the embryo.
In mosses and ferns, eggs develop in archegoniums, in flowering plants - in ovules localized in the ovary of the flower.
EXAMPLES OF TASKS
Part A
A1. Meiosis is the process
1) changes in the number of chromosomes in a cell
2) doubling the number of chromosomes in a cell
3) the formation of gametes
4) conjugation of chromosomes
A2. At the heart of changes in the hereditary information of children
compared to parent information are processes
1) doubling the number of chromosomes
2) halving the number of chromosomes
3) doubling the amount of DNA in cells
4) conjugation and crossing over
A3. The first division of meiosis ends with the formation of:
2) cells with a haploid set of chromosomes
3) diploid cells
4) cells of different ploidy
A4. Meiosis produces:
1) fern spores
2) cells of the walls of the fern antheridium
3) cells of the walls of the archegonium of the fern
4) somatic cells of drone bees
A5. Metaphase of meiosis can be distinguished from metaphase of mitosis by
1) the location of the bivalents in the plane of the equator
2) duplication of chromosomes and their twisting
3) the formation of haploid cells
4) divergence of chromatids to the poles
A6. The telophase of the second division of meiosis can be recognized by
1) the formation of two diploid nuclei
2) divergence of chromosomes to the poles of the cell
3) the formation of four haploid nuclei
4) doubling the number of chromatids in a cell
A7. How many chromatids will be contained in the nucleus of rat spermatozoa, if it is known that the nuclei of its somatic cells contain 42 chromosomes
1) 42 2) 21 3) 84 4) 20
A8. The gametes formed as a result of meiosis are
1) copies of the complete set of parental chromosomes
2) copies of half the set of parental chromosomes
3) a complete set of recombined parental chromosomes
4) half of the recombined set of parental chromosomes
Part B
IN 1. The biological significance of meiosis is to maintain the constancy of the species number of chromosomes, create conditions for combinative variability, arbitrary divergence of parental chromosomes by gametes, preserve parental hereditary information without changes, increase the number of chromosomes in the cell, preserve useful features of the organism during reproduction.
IN 2. Establish a correspondence between the process and the events that occur during this process
VZ. Set the correct sequence of processes occurring in meiosis
A) Location of bivalents in the plane of the equator
B) Formation of bivalents and crossing over
B) Divergence of homologous chromosomes to the poles of the cell
D) the formation of four haploid nuclei
E) the formation of two haploid nuclei containing two chromatids each
Part C
C1. Meiosis underlies combinative variability. What explains this?
C2. Compare the results of mitosis and meiosis
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G.I. lerner
Biology
A complete guide to preparing for the exam
The Unified State Examination is a new form of attestation that has become mandatory for high school graduates. Preparation for the exam requires students to develop certain skills in answering the proposed questions and skills in filling out exam forms.
This complete guide to biology provides all the materials you need to prepare well for the exam.
1. The book includes the theoretical knowledge of basic, advanced and high levels of knowledge and skills tested in examination papers.
3. The methodological apparatus of the book (examples of tasks) is focused on testing the knowledge and certain skills of students in applying this knowledge both in familiar and new situations.
4. The most difficult questions, the answers to which cause difficulties for students, are analyzed and discussed in order to help students cope with them.
5. The sequence of presentation of educational material begins with "General Biology", because. the content of all other courses in the examination paper is based on general biological concepts.
At the beginning of each section, KIMs are cited for this section of the course.
Then the theoretical content of the topic is presented. After that, examples of test tasks of all forms (in different proportions) encountered in the examination paper are offered. Particular attention should be paid to the terms and concepts that are in italics. They are the first to be tested in the examination papers.
In a number of cases, the most difficult issues are analyzed and approaches to their solution are proposed. Answers to Part C provide only elements of the correct answers that will allow you to clarify information, supplement it, or give other arguments in favor of your answer. In all cases, these answers are sufficient to pass the exam.
The proposed textbook on biology is addressed primarily to schoolchildren who have decided to take the unified state exam in biology, as well as teachers. At the same time, the book will be useful to all schoolchildren of a comprehensive school, because will allow not only to study the subject within the school curriculum, but also to systematically check its assimilation.
Biology is the science of life
1.1. Biology as a science, its achievements, research methods, connections with other sciences. The role of biology in the life and practical activities of man
Terms and concepts tested in the examination papers for this section: hypothesis, research method, science, scientific fact, object of research, problem, theory, experiment.
Biology The science that studies the properties of living systems. However, it is rather difficult to define what a living system is. That is why scientists have established several criteria by which an organism can be classified as living. Chief among these criteria are metabolism or metabolism, self-reproduction and self-regulation. A separate chapter will be devoted to the discussion of these and other criteria (or) properties of the living.
concept the science is defined as "the sphere of human activity to obtain, systematize objective knowledge about reality." In accordance with this definition, the object of science - biology is a life in all its manifestations and forms, as well as on different levels .
Every science, including biology, uses certain methods research. Some of them are universal for all sciences, such as observation, proposing and testing hypotheses, and building theories. Other scientific methods can only be used by a particular science. For example, geneticists have a genealogical method for studying human pedigrees, breeders have a hybridization method, histologists have a tissue culture method, etc.
Biology is closely related to other sciences - chemistry, physics, ecology, geography. Biology itself is divided into many special sciences that study various biological objects: plant and animal biology, plant physiology, morphology, genetics, taxonomy, breeding, mycology, helminthology and many other sciences.
Method- this is the path of research that a scientist goes through, solving any scientific problem, problem.
The main methods of science include the following:
Modeling- a method in which a certain image of an object is created, a model with the help of which scientists obtain the necessary information about the object. So, for example, when establishing the structure of the DNA molecule, James Watson and Francis Crick created a model from plastic elements - a DNA double helix that corresponds to the data of X-ray and biochemical studies. This model fully met the requirements for DNA. ( See section Nucleic acids.)
G.I. lerner
Biology
A complete guide to preparing for the exam
The Unified State Examination is a new form of attestation that has become mandatory for high school graduates. Preparation for the exam requires students to develop certain skills in answering the proposed questions and skills in filling out exam forms.
This complete guide to biology provides all the materials you need to prepare well for the exam.
1. The book includes the theoretical knowledge of basic, advanced and high levels of knowledge and skills tested in examination papers.
3. The methodological apparatus of the book (examples of tasks) is focused on testing the knowledge and certain skills of students in applying this knowledge both in familiar and new situations.
4. The most difficult questions, the answers to which cause difficulties for students, are analyzed and discussed in order to help students cope with them.
5. The sequence of presentation of educational material begins with "General Biology", because. the content of all other courses in the examination paper is based on general biological concepts.
At the beginning of each section, KIMs are cited for this section of the course.
Then the theoretical content of the topic is presented. After that, examples of test tasks of all forms (in different proportions) encountered in the examination paper are offered. Particular attention should be paid to the terms and concepts that are in italics. They are the first to be tested in the examination papers.
In a number of cases, the most difficult issues are analyzed and approaches to their solution are proposed. Answers to Part C provide only elements of the correct answers that will allow you to clarify information, supplement it, or give other arguments in favor of your answer. In all cases, these answers are sufficient to pass the exam.
The proposed textbook on biology is addressed primarily to schoolchildren who have decided to take the unified state exam in biology, as well as teachers. At the same time, the book will be useful to all schoolchildren of a comprehensive school, because will allow not only to study the subject within the school curriculum, but also to systematically check its assimilation.
Biology is the science of life
1.1. Biology as a science, its achievements, research methods, connections with other sciences. The role of biology in the life and practical activities of man
Terms and concepts tested in the examination papers for this section: hypothesis, research method, science, scientific fact, object of research, problem, theory, experiment.
Biology The science that studies the properties of living systems. However, it is rather difficult to define what a living system is. That is why scientists have established several criteria by which an organism can be classified as living. Chief among these criteria are metabolism or metabolism, self-reproduction and self-regulation. A separate chapter will be devoted to the discussion of these and other criteria (or) properties of the living.
concept the science is defined as "the sphere of human activity to obtain, systematize objective knowledge about reality." In accordance with this definition, the object of science - biology is a life in all its manifestations and forms, as well as on different levels .
Every science, including biology, uses certain methods research. Some of them are universal for all sciences, such as observation, proposing and testing hypotheses, and building theories. Other scientific methods can only be used by a particular science. For example, geneticists have a genealogical method for studying human pedigrees, breeders have a hybridization method, histologists have a tissue culture method, etc.
Biology is closely related to other sciences - chemistry, physics, ecology, geography. Biology itself is divided into many special sciences that study various biological objects: plant and animal biology, plant physiology, morphology, genetics, taxonomy, breeding, mycology, helminthology and many other sciences.
Method- this is the path of research that a scientist goes through, solving any scientific problem, problem.
The main methods of science include the following:
Modeling- a method in which a certain image of an object is created, a model with the help of which scientists obtain the necessary information about the object. So, for example, when establishing the structure of the DNA molecule, James Watson and Francis Crick created a model from plastic elements - a DNA double helix that corresponds to the data of X-ray and biochemical studies. This model fully met the requirements for DNA. ( See section Nucleic acids.)
Observation- the method by which the researcher collects information about the object. You can observe visually, for example, the behavior of animals. It is possible to observe with the help of devices the changes taking place in living objects: for example, when taking a cardiogram during the day, when measuring the weight of a calf during a month. You can observe seasonal changes in nature, the molting of animals, etc. The conclusions drawn by the observer are verified either by repeated observations or experimentally.
Experiment (Experience)- a method by which the results of observations, put forward assumptions are checked - hypotheses . Examples of experiments are crossing animals or plants in order to obtain a new variety or breed, testing a new drug, identifying the role of some cell organelle, etc. An experiment is always the acquisition of new knowledge with the help of a given experience.
Problem- a question, a problem that needs to be solved. Problem solving leads to new knowledge. A scientific problem always hides some contradiction between the known and the unknown. Solving the problem requires the scientist to collect facts, analyze them, and systematize them. An example of a problem is, for example, the following: “How does the adaptation of organisms to the environment arise?” or “How can I prepare for serious exams in the shortest possible time?”.
It can be quite difficult to formulate a problem, but whenever there is a difficulty, a contradiction, a problem appears.
Hypothesis- an assumption, a preliminary solution to the problem. Putting forward hypotheses, the researcher is looking for relationships between facts, phenomena, processes. That is why the hypothesis most often takes the form of an assumption: "if ... then." For example, “If plants emit oxygen in the light, then we can detect it with the help of a smoldering torch, because. oxygen must support combustion. The hypothesis is tested experimentally. (See Hypotheses for the Origin of Life on Earth.)
Theory is a generalization of the main ideas in any scientific field of knowledge. For example, the theory of evolution summarizes all the reliable scientific data obtained by researchers over many decades. Over time, theories are supplemented by new data, develop. Some theories may be refuted by new facts. True scientific theories are confirmed by practice. So, for example, the genetic theory of G. Mendel and the chromosome theory of T. Morgan were confirmed by many experimental studies in different countries of the world. The modern evolutionary theory, although it has found many scientifically proven confirmations, still meets opponents, because. not all of its provisions can be confirmed by facts at the present stage of development of science.
Private scientific methods in biology are:
genealogical method - used in the compilation of pedigrees of people, identifying the nature of inheritance of certain traits.
historical method - establishing relationships between facts, processes, phenomena that have occurred over a historically long time (several billion years). The evolutionary doctrine has developed largely due to this method.
paleontological method - a method that allows you to find out the relationship between ancient organisms, the remains of which are in the earth's crust, in different geological layers.
centrifugation – separation of mixtures into component parts under the action of centrifugal force. It is used in the separation of cell organelles, light and heavy fractions (components) of organic substances, etc.
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