Tasks in genetics for incomplete and complete dominance. Independent inheritance with incomplete dominance In snapdragons, the red color gene

A man with Rh and 4 blood types married a woman with Rh + and 3 blood types. The woman's father had Rh and 1 blood type.

Given: D, Rh gene

d - Rh gene

I A \u003d I B\u003e I 0

R: ♀ DdI B I 0 x ♂ ddI B I A

G: DI B, DI 0 , dI B, dI 0 dI B, dI A

F: DdI B I B, DdI A I B, DdI B I 0 , DdI A I 0

ddI B I B, ddI A I B, ddI B I 0 , ddI A I 0

A child with Rh + and 1 blood type is illegitimate

Codominance

Task #18

Rabbits have a series of multiple alleles that determine coat color. The wild color gene (agouti) C dominates all other colors.

Given: C - wild color gene c ch - chinchilla color gene

c - white color gene c h - Himalayan color gene

R: ♀ Сс x ♂ cc hс

G: C, c c, c ch

F: ss, ss ch, ss, cc hс

agouti white chinchilla 2:1:1

Laws: independent combination of traits, purity of gametes

Task #19

In snapdragons, the red color of the flowers partially dominates the white color, so that the hybrids have pink flowers. Narrow leaves partially dominate over wide leaves - in hybrids, leaves have an intermediate width.

Given: A - gene for red color B - gene for narrow leaves

a - gene for white color c - gene for wide leaves

R: ♀ AABv x ♂ AaVv

G: AB, AB AB, AB, AB, AB,

F: AABB - red flowers, narrow leaves

AaBB - pink flowers, narrow leaves

AABv - red flowers, intermediate leaves

AAvv - red flowers, wide leaves

AaBv - pink flowers, intermediate leaves

Aavv - pink flowers, wide leaves

Laws: independent combination of traits, purity of gametes

Task #20

In minks, the brown color of the fur dominates over the blue. A brown female was crossed with a blue male. Among the offspring, two puppies are brown and one blue.

Given: A - brown color gene

a - blue color gene

R: ♀ Aa x ♂ aa

The female is not purebred, because splitting is observed in the offspring

Interaction of genes - complete dominance

Task #21

They crossed a motley rooster and a chicken. Received 26 motley, 12 black and 13 white chickens. How is plumage color in chickens inherited?

Given: A - black color gene

a - gene for white color

R: ♀ Aa x ♂ Aa

G: A, a A, a

F: AA, Aa, Aa, aa

black mottled white 1:2:1

Laws: splitting, purity of gametes

Interaction of genes - incomplete dominance

Task #22

Platinum foxes are sometimes valued above gray foxes. Which pairs are most profitable to cross to obtain platinum foxes, if it is known that platinum and silver are determined by allelic genes, platinum dominates over silver, but in the homozygous state, the platinum gene causes the death of the embryo.

Given: A - platinum color gene

a - gray color gene

R: ♀ Aa x ♂ aa

50% chance of getting Platinum Foxes

Laws: splitting, purity of gametes

Interaction of genes - pleiotropy

Task #23

Polydactyly (six-fingeredness), myopia, and the absence of small molars are transmitted as dominant autosomal traits.

Given: A - gene for polydactyly B - gene for myopia C - gene for the absence of small molars

a - normal gene b - normal gene c - normal gene

R: ♀ AaVvSs x ♂ AaVvSs

G: ABC, aBC ABC, aBC

ABC, ABC ABC, ABC

Avs, avs Avs, avs

F: A_ B_C_ - polydactyly, myopia, absent. box teeth 3 3 =27/64

A_ B_ ss - polydactyly, myopia, norm 3 2 = 9/64

A_ cc C_ - polydactyly, normal, absent. box teeth 3 2 =9/64

A_ vvss - polydactyly, norm, norm 3 1 = 3/64

aaB_C_ - norm, myopia, absent. box teeth 3 3 =27/64

aaB_ ss - norm, myopia, norm 3 1 = 3/64

aa cc C_ - norm, norm, absent. box teeth 3 2 =9/64

aavvss - norm, norm, norm 3 0 =1/64

Probability of birth healthy children - 1,56%

Laws: independent combination of traits, gamete frequency

Interaction of genes - complete dominance

Task #24

Healthy parents with the 4th blood group according to the AB0 system gave birth to a son with the 2nd blood group and suffering from mucopolysaccharidosis (an autosomal disease.

Given: M – normal gene

m – mucopolysaccharidosis gene

I A \u003d I B\u003e I 0

R: ♀ MmI A I B x ♂ MmI A I B

G: MI A, MI B MI A, MI B

mI A, mI B mI A, mI B

F: MMI A I A, MMI A I B , MmI A I A , MmI A I B

MMI A I B , MMI B I B , MmI A I B , MmI B I 0

MmI A I A , MmI A I B, mmI A I A , mmI A I B

MmI A I B, MmI B I B, mm I А I B , mm I B I B

The probability of having healthy children is 75% with 2, 3, 4 blood groups

Laws: independent combination of traits, purity of gametes

Task #25

Hereditary goiter is a genetically heterogeneous disease, i.e. inherited in an autosomal recessive and autosomal dominant manner. Determine the probability of having sick children in spouses who are diheterozygous for both genes. What laws of genetics did they use to solve the problem? Name the type of interaction between allelic genes.

Given: A - normal gene B - disease gene

a - disease gene c - normal gene

R: ♀ AaVv x ♂ AaVv

G: AB, AB, AB, AB AB, AB, AB, AB,

F: A_B_ - hereditary goiter 3 2 = 9/16

A_ cc - norm 3 1 \u003d 3/16

aa B_ - hereditary goiter 3 1 = 3/16

aavv - hereditary goiter 3 0 = 1/16

The probability of having children with goiter - 81.25%, healthy - 18.75%

Laws: independent combination of traits, purity of gametes

Interaction of genes - complete dominance

Task #26

In healthy parents, the first child died in early age from cystic fibrosis. The second child in the family died of this disease, at the time when the third was due to be born.

Given: A - normal gene

a - cystic fibrosis gene

R: ♀ Aa x ♂ Aa

G: A, a A, a

F: Ah, ah, ah, aa

normal cystic fibrosis

The probability of having a healthy child is 75%

Laws: splitting, purity of gametes

Interaction of genes - complete dominance

If both pairs of genes are inherited incomplete dominance, then the splitting by phenotype and genotype will coincide with each other. If incomplete dominance carried out on one pair of genes, then the coincidence of genotypes or phenotypes will occur only on it.

Task 4-35

In chickens, the pea comb gene (A) dominates over the simple comb gene (a), and incomplete dominance is observed for the genes for black (B) and white (b) color: individuals with the Bb genotype are blue in color. If you cross birds that are heterozygous for both pairs of genes, then what proportion of offspring will have:
a) a simple comb;
b) blue color;
c) a simple crest and blue coloring;
d) white color and pea-shaped comb?

Since each of the traits is inherited independently of each other, there will be 1/4 chickens with a simple comb, 1/2 chickens with a blue color.

Determining the number of individuals with two traits is reduced to the construction of the Punnett lattice, from which the following can be seen:
1/8 of the offspring will have the aaBb genotype (simple crest, blue color);
3/16 of the offspring will have the genotype AAbb and Aabb (pea comb, white coloring).

Hens with a simple comb will be 1/4, with a blue color - 1/2, with a simple comb and blue color - 1/8, with a pea-shaped comb and white color - 3/16.

Task 4-36

What phenotypic splitting will be observed when two diheterozygotes are crossed if:
a) both genes do not completely dominate their allele;
b) dominance is complete for one pair of genes, and incomplete for the other?

Task 4-37

In snapdragons, flower color is controlled by one pair of genes with incomplete dominance, and leaf width by another pair of genes with incomplete dominance. Both pairs of genes are inherited independently. What ratio of genotypes and phenotypes will be obtained in the offspring from crossing plants with red flowers and medium leaves and with pink flowers and narrow leaves

Task 4-38

In snapdragons, the red color of the flower incompletely dominates the white. The hybrid plant has a pink color. The normal form of the flower completely dominates the pyloric. What offspring will result from crossing two heterozygous plants?

Task 4-39

In the Shorthorn cattle breed, coat color is inherited according to an intermediate type: the R gene determines the red color, the r gene determines white; Rr genotypes have roan coats. Polled (P) dominates over hornedness (p). White horned cow crossed with homozygous red horned bull. What phenotype and genotype will their offspring F 1 and F 2 have?

Task 4-40

In snapdragons, the red color of the flower incompletely dominates the white. The hybrid plant has a pink color. Narrow leaves partially dominate over wide ones (in hybrids, the leaves are of medium width). What offspring will result from crossing a plant with red flowers and medium leaves with a plant with pink flowers and medium leaves?

Task 4-41

In cattle, polledness dominates horniness, and coloration is controlled by a pair of genes with incomplete dominance - homozygous animals have a red or white color, and heterozygous animals have a roan. Crossing a roan bull with a horned white cow produced a horned roan heifer. What are the genotypes of all these animals?

1.77. In wheat, the length of the ear is inherited according to an intermediate type, and awnlessness dominates over awn. What gametes and what offspring will be produced in the first and second generations by crossed plants of wheat with a long awnless ear and awned wheat with a short ear?

1.78. The color of flowers in the night beauty is inherited according to an intermediate type, and the height of the plant dominates over dwarfism. A homozygous plant of the night beauty with red flowers was crossed, normal growth and a plant that has white flowers, dwarf growth. What gametes will the parent plants and plants of the first generation produce? What splitting will be observed in the second generation?

1.79. In cattle of the Latvian breed, the genes for red and white wool in the heterozygous state give a roan color, and hornlessness dominates over horniness. What offspring will be from crossing a roan horned cow with a roan hornless bull?

1.80. Snapdragons have red flowers A partially dominant over white coloration A / so that the hybrids have pink flowers. narrow leaves H partially dominate broad leaves H / - in hybrids, the leaves have an intermediate width. Plants with red flowers and medium leaves are crossed with plants with pink flowers and medium leaves. What will be the phenotype and genotype of the offspring from this cross?

1.81. Chickens have the pea comb gene ( R) dominates the simple comb gene ( R), and for black genes ( IN) and white ( B / ) coloration, incomplete dominance is observed: individuals with the genotype BB / are blue in color. If you cross birds that are heterozygous for both pairs of genes, then what proportion of offspring will have:

a) simple comb

b) blue color

c) white color

d) white color and pea-shaped comb,

e) blue coloring and a simple crest?

1.4. Interaction of non-allelic genes.

1.82. Deafness in humans may be due to recessive genes d And e located on different pairs of chromosomes. Normal hearing requires the presence of both dominant genes. deaf woman DDee) marries a deaf man ( ddee). Will their children be deaf?

Solution.

P♀ DDee x ♂ ddee

Since the dominant genes from each pair are found in the zygote, all children will have normal hearing.

1.83. In most breeds of chickens, the colored plumage determines the gene WITH, white plumage is its allele With. The Leghorn breed has an epistatic gene I, suppressing pigment development even in the presence of the gene WITH. its allele i no such effect is exerted by the action of the gene WITH appears.

Two white heterozygous individuals are crossed. Determine the splitting by phenotype in offspring.

Solution.

P♀ CcIi x ♂ CcIi

F19 C_I_, 3 C_ ii, 3 ccI_, 1 cc ii

white painted white white

13:3 ratio

1.84. Human growth is controlled by three pairs of unlinked genes that interact like a polymer. The shortest people have all recessive genes and are 150 cm tall, the tallest are all dominant and 180 cm tall.

Determine the height of people heterozygous for three pairs of genes: A1a1A2a2A3a3 .

Solution .


Tall, 180 cm	A1, A2, A3	A1A1A2A2A3A3
Low rise, 150 cm	A1, a2, a3	A1a1a2a2a3a3

Their height will be average growth of homozygotes for dominant and recessive genes - 165 cm.

1.85. When crossing a chicken with a pea-shaped and a rooster with a rose-shaped comb, all first-generation hybrids have a nut-shaped comb, which is obtained due to the interaction of two dominant alleles A And IN.

What offspring will be when F1 individuals are crossed with each other? What will be the offspring of an F1 hybrid crossed with a homozygous individual with a pink crest?

1.86.* When two pumpkin plants with disc-shaped and elongated fruits were crossed, plants with disc-shaped, round and elongated fruits were obtained. What are the genotypes of the parent plants? What part of the offspring should have a round fruit shape?

1.87.* The inheritance of color in horses is determined by the interaction of two non-allelic genes by the type of epistasis. When crossing gray and black horses, a red foal was obtained. What are the genotypes of the parents? Using the data in table 1.2. on page 4, indicate whether this gene interaction is a dominant or recessive epistasis.

1.88. In chickens - white leghorns - plumage color is controlled by two groups of genes:

W(white coloration) dominates w(color),

IN(black coloration) dominates b(brown).

Heterozygous F1 offspring have the genotype wwbb and white color.

Explain the interaction between genes that occurs in this case and indicate the numerical ratios of phenotypes in the F2 generation.

1.89.* The weight of the fetus in one variety of pumpkin is determined by three pairs of genes, moreover, the combination AABBSS gives fruits weighing 3 kg, and the combination aabbcc- fruits weighing 1.5 kg. Each dominant gene adds 250 g to the weight of the fetus. When crossing 3-kilogram pumpkins with 1.5-kilogram ones, all descendants produce fruits weighing 2.25 kg. What would be the fruit weight of an F2 if two such F1 plants were crossed?

1.5. Linked inheritance and crossing over.

1.90. What types of gametes are formed in organisms that have genotypes:

AB Ab aB AbCd

== , == , == , ==== (no crosshair)?

ab aB AB aBcD

Solution.

AB Ab aB

ab aB AB

1.91. Determine the differences in the numerical ratio of the resulting gametes in two organisms with the following genotype structure:

A B AB

1) == == , 2) === .

Solution. In the first organism, allelic genes are not linked and are inherited independently. It produces four varieties of gametes in equal amounts (25% AB,25% Ab,25% aB,25%ab). The second has gene linkage. This organism gives two varieties of gametes at full linkage (50% AB and 50% ab). With incomplete linkage of genes, four varieties of gametes will be formed; of which non-crossover AB, Ab in quantities greater than 25% and crossover Ab And aB– less than 25%.

Question: In snapdragons, the gene (R) for red flowers is not completely dominant over the gene (r) for white. In this case, the interaction of the allelic genes R and r gives a pink color. Determine the color of the flowers and the ratio of phenotypes according to the color in the offspring obtained as a result of the following crosses: 1) Rr x Rr 2) RR x Rr 3) RR x rr 4) RR x rr with the solution please.

Question:

In snapdragons, the gene (R) for red flower color does not completely dominate the gene (r) for white color. In this case, the interaction of the allelic genes R and r gives a pink color. Determine the color of the flowers and the ratio of phenotypes according to the color in the offspring obtained as a result of the following crosses: 1) Rr x Rr 2) RR x Rr 3) RR x rr 4) RR x rr with the solution please.

Answers:

1. R r R RR Rr r Rr rr Genotypes: RR, Rr,rr. Phenotypes: Red: Pink: White Ratio: 1:2:1 (25%:50%:25%) 2. R R R RR RR r Rr Rr Genotypes: RR, Rr. Phenotypes: Red: pink Ratio: 1:1 (50%:50%) 3. R R r Rr Rr r Rr Rr Genotypes: Rr Phenotypes: Pink All flowers will be pink 4. Same solution as in the third task