Exercise 1 . Match.

Task 2. How many allelic pairs are there in the following genotypes?

• AaVvssDd
• AaddCcDdee

Task 3. How many dominant genes are there in genotypes?

• aaВВСс
• ААввСсDDee
• AaBbccDdEe

Task 4. How many heterozygous alleles are there in the genotypes?

• AavvSss
• AAVvss
• AABvCCddEe

Task 5. Will a dominant or recessive trait appear in individuals with this genotype?

• AAVvss
• aaВвСсDDEe
• aaBbccDdee

Problems on the topic “Monohybrid crossing”

Task 1.

Task 2.

In guinea pigs, black coat color is dominant over white. Two heterozygous males and a female were crossed. What will the first generation hybrids be like?

Task 3.

Task 4.

* Task 5.

* Task 6.

In tomatoes, normal plant height dominates dwarf growth. What are the genotypes of the parents if 50% of the offspring turned out to be of normal height and 50% of short height?

* Task 7.

When two white pumpkins were crossed in the first generation, ¾ of the plants were white and ¼ were yellow. What are the genotypes of the parents if white color is dominant over yellow?

Task 8.

Task 9.

Problem 10.

The Firebird has bright yellow plumage, the Bluebird has bluer plumage. When the Firebird was crossed with the Bluebird, blue chicks hatched. Which trait is dominant? What are the genotypes of the parents and offspring?

Problem 11.

Problem 12. ʼʼA Tale of Dragonsʼʼ

1. Fire-breathing parents - all offspring are fire-breathing.

2. Non-fire-breathing parents - all offspring are non-fire-breathing.

3. A fire-breathing male and a non-fire-breathing female - the offspring contain approximately equal numbers of fire-breathing and non-fire-breathing dragonets.

4. A non-fire-breathing male and a fire-breathing female - all offspring are non-fire-breathing.

Assuming that the trait is determined by an autosomal gene, establish the dominant allele and write down the genotypes of the parents.

Problems on the topic “Incomplete dominance”

Problem 13.

When purebred white chickens are crossed with each other, the offspring turns out to be white, and when black chickens are crossed, the offspring turns out to be black. The offspring of a white and black individual turns out to be variegated. What plumage will the offspring of a white rooster and a motley hen have?

Problem 14.

These varieties together produce pink berries. What offspring will arise when hybrids with pink berries are crossed with each other?

Problems on the topic “Di- and polyhybrid crossing”

Problem 15.

A blue-eyed, right-handed young man (his father was left-handed), married a brown-eyed, left-handed woman (all her relatives are brown-eyed). What possible children will there be from this marriage, if brown eyes and right-handedness are dominant characteristics?

Problem 16.

Rabbits were crossed: a homozygous female with normal hair and drooping ears and a homozygous male with long hair and erect ears. What will the first generation hybrids be like if regular fur and erect ears are dominant traits?

Problem 17.

Problem 18.

In a figured pumpkin, the white color of the fruit dominates over the yellow one, and the disc-shaped shape dominates over the spherical one. What will the hybrids look like from crossing a homozygous yellow spherical pumpkin and a yellow discoid pumpkin (heterozygous for the second allele).

Problem 19.

In tomatoes, the red color of the fruit dominates over yellow,

normal growth is above dwarf growth. What will be the hybrids from crossing homozygous yellow tomatoes of normal growth and yellow dwarfs?

* Problem 20.

What are the genotypes of the parent plants if, when crossing red tomatoes (dominant trait) pear-shaped (recessive trait) with yellow spherical ones, the result is: 25% red spherical, 25% red pear-shaped, 25% yellow spherical, 25% yellow pear-shaped?

Problem 21.

recessive r.
Posted on ref.rf
What will be the first generation phenotype when crossing a homozygous white walking unicorn with a homozygous yellow trotter? What offspring and in what proportions will be obtained by crossing two first-generation individuals?

Task 22. ʼʼConsultant of the company ʼʼCocktailʼʼ

Imagine that you are a consultant for a small company called “Cocktail”, which literally translated from English means “cocktail”. The company breeds exotic breeds of roosters for their tail feathers, which are readily purchased by hat store owners all over the world. The length of the feathers is determined by the gene A (long) and a (short), color: B - black, b - red, width: C - wide, c - narrow. The genes are not linked. There are many different roosters and hens on the farm with all possible genotypes, the data about which is entered into the computer.
Posted on ref.rf
Next year, increased demand for hats with long black narrow feathers is expected. What crosses should be made to get the maximum number of birds with fashionable feathers in the offspring? It is not worth crossing pairs with absolutely identical genotypes and phenotypes.

Problems on the topic “Inheritance of blood groups”

Problem 23.

What blood types do children have if both parents have blood type 4?

Problem 24.

Is it possible to transfuse blood to a child from the mother if she has blood type AB and the father has O?

Problem 25.

The boy has blood type 4, and his sister has blood type 1. What are the blood types of their parents?

* Problem 26.

In the maternity hospital, two boys (X and Y) were mixed up. X has the first blood group, Y has the second. The parents of one of them are with blood groups 1 and 4, and the other is with blood groups 1 and 3. Who is whose son?

Problem 27.

Problem 28.

A miller died in the village. Having buried my father,

The inheritance was shared by three young brothers:

The elder brother took the mill, the second took the donkey,

And the cat went to the younger brother - the younger brother took the cat.

Problem 29.

Thumb has blood type AB, his mother has blood type AO. What blood type can the father have?

Problems on the topic “Sex-linked inheritance”

Problem 30.

What kind of vision should the children of a marriage between a man and a woman who normally distinguish colors have, if it is known that their fathers suffered from color blindness?

Problem 31.

Can the children of a man with hemophilia and a woman without anomalies (whose father had hemophilia) be healthy?

Problem 32.

Problem 33.

* Problem 34.

Husbands and wives who are healthy with respect to hemophilia have

A son with hemophilia who has a healthy daughter

A healthy daughter who has 2 sons: one has hemophilia and the other is healthy,

A healthy daughter who has five healthy sons

What are the genotypes of this husband and wife?

Problem 35.

Problem 36.

Problem 37.

is it likely that they would have a sweet tooth? Solve two versions of the problem: dad loves sweets and doesn’t.

Problem 38.

The Ryaba hen can lay golden and simple eggs. The recessive gene for gold-bearing eggs is located on the X chromosome. What should be the genotypes of the Hen and the Rooster so that all of their Ryaba Hens lay golden eggs?

Problem 39. ʼʼWill Prince Uno's wedding be upset?ʼʼ

The only crown prince, Uno, is about to marry the beautiful princess Beatrice. Uno's parents learned that there were cases of hemophilia in Beatrice's family. Beatrice has no brothers or sisters. Aunt Beatrice has two healthy, strong sons. Uncle Beatrice spends his days hunting and feels great. The second uncle died as a boy from loss of blood, the cause of which was a deep scratch. Uncles, aunts and Beatrice’s mother are children of the same parents. How likely is it that the disease can be transmitted through Beatrice to the royal family of her fiancé?

Problem 40. ʼʼRoyal dynastiesʼʼ

Let's assume that Emperor Alexander II had a rare mutation on his Y chromosome. Could this mutation have been present in: a) Ivan the Terrible

b) Petra I

c) Catherine II

d) Nicholas ΙΙ?

Problem 41 . ʼʼLeafing through the novel ʼʼWar and Peaceʼʼ

Let's assume that Prince Nikolai Andreevich Bolkonsky had a rare mutation on the X chromosome. Pierre Bezukhov had the same mutation. With what probability could this mutation be present in: a) Natasha Rostova

b) the son of Natasha Rostova

c) son of Nikolai Rostov

Combined tasks

Problem 42.

parents from crossing a heterozygous polled roan bull with a white horned cow.

Problem 43.

Problem 44.

In one family, 4 children were born to brown-eyed parents: two blue-eyed with 1 and 4 blood groups, two brown-eyed with 2 and 4 blood groups. Determine the probability of the next child being born with brown eyes and blood group 1.

Problem 45.

A man with blue eyes and normal vision married a woman with brown eyes and normal vision (all of her relatives had brown eyes, and her brother was color blind). What are the children from this marriage like?

Problem 46.

absence - from an autosomal recessive gene. Both parents are green with tufts. They had 2 chicks: a green male with a crest and a brown female without a crest. Determine the genotypes of the parents.

Problem 47.

A man suffering from color blindness and deafness married a woman who can hear well and has normal vision. They had a son who was deaf and color blind and a daughter who had good hearing and was color blind. Is it possible for this family to have a daughter with both anomalies, if deafness is an autosomal recessive trait?

Problems on the topic “Interaction of genes”

Problem 48.

dominant, and the other in a recessive state determines the development of either a rose-shaped or pisiform comb; individuals with a simple comb are recessive for both alleles. What will the offspring be like when crossing two diheterozygotes?

Problem 49.

The brown fur color of minks is due to the interaction of dominant alleles. Homozygosity for recessive alleys of one or two of these genes gives platinum coloring. What will be the hybrids from crossing two diheterozygotes?

* Problem 50.

In alfalfa, the inheritance of flower color is the result of the complementary interaction of two pairs of non-allelic genes. When crossing plants of pure lines with purple and yellow flowers in the first generation, all plants had green flowers, in the second generation a split occurred: 890 plants grew with green flowers, 306 with yellow, 311 with purple and 105 with white. Determine the genotypes of the parents.

Problem 51.

the dominant allele determines the gray color (because it causes an uneven distribution of pigment along the length of the hair: the pigment accumulates at its base, while the tip of the hair is devoid of pigment), the recessive allele determines the black color (because it does not affect pigment distribution). What will the offspring be like from crossing two diheterozygotes?

* Problem 52.

In oats, grain color is determined by the interaction of two non-allelic genes. One dominant determines the black color of the grains, the other – gray. The black gene suppresses the gray gene. Both recessive alleles produce white coloration. When crossing black-grain oats, the offspring showed a split: 12 black-grain: 3 gray-grain: 1 with white grains. Determine the genotypes of the parent plants.

Problem 53.

Human skin color is determined by the interaction of genes according to the type of polymer: the darker the skin color, the more dominant genes in the genotype: if there are 4 dominant genes, the skin is black, if 3 are dark, if 2 are dark, if 1 is light. , if all genes are in a recessive state - white. A black woman married a white man. What will their grandchildren be like if their daughter marries a mulatto (AaBv)?

Problem 54.

Inheritance of springiness in wheat is controlled by one or two dominant polymer genes, and winterness is controlled by their recessive alleles. What will the offspring be like when crossing two diheterozygotes?

Problem 55.

Talker birds are distinguished by their intelligence and intelligence. The crests on the head are white and red (red color is inherited by two pairs of genes). Two birds with white crests cross, and they hatch a chick with a red crest on its head. What are the genotypes of the parents and the chick?

Problem 56.

On the Third Planet of the Medusa system, Alisa Selezneva discovered flowers with a regular core and a mirror core (the mirror core is determined by two pairs of genes). Is it possible to get flowers with a mirror core if you cross two plants with regular cores? With what genotypes of parents?

Problem 57. "The dispute between Bender and Panikovsky"

Two neighbors argued: how is color inherited in budgies? Bender believes that the color of parrots is determined by one gene, which has 3 alleles: C o - recessive in relation to the other two, C g and C g are codominant. For this reason, parrots with the genotype C o C o have a white color, C g C g and C g C o - blue, C g C g and C g C o - yellow color and C g C g - green color. And Panikovsky believes that color is formed under the influence of two interacting genes A and B. For this reason, parrots with the A*B* genotype are green, A* bb are blue, aaB* are yellow, aabv are white.

Οʜᴎ consisted of 3 genealogies:

1. P: Z x B 2. P: Z x Z 3. P: W x B

F 1: Z, B F 1: B F 1: G, F, G, G, F, F, F, G, F

Which genealogies could have been compiled by Bender, which by Panikovsky?

Problems on the topic “Analyzing Crossing”

Problem 58.

colors, the second has 5 fox cubs: 2 red and 3 black-brown. What are the genotypes of all parents?

Problem 59.

puppies: 2 short-haired black and 2 short-haired coffee. What is the genotype of the dog purchased by the hunter?

Problem 60. smuggler

In the small state of Lisland, foxes have been bred for several centuries. Fur is exported, and money from its sale forms the basis of the country's economy. Silver foxes are especially prized. Οʜᴎ are considered a national treasure, and transport across borders is strictly prohibited. A cunning smuggler who did well in school wants to deceive customs. He knows the basics of genetics and suggests that the silver coloration of foxes is determined by two recessive alleles of the coat color gene. Foxes with at least one dominant allele are red. What needs to be done to get silver foxes in the smuggler’s homeland without violating the laws of Lisland?

Tasks on the topic

ʼʼChained inheritance (crossing over)ʼʼ

Problem 61.

Determine the frequency (percentage) and types of gametes in a diheterozygous individual, if it is known that genes A and B are linked and the distance between them is 20 Morganidae.

Problem 62.

In tomatoes, tall growth dominates over dwarf growth, and the spherical shape of the fruit dominates over pear-shaped. The genes responsible for these traits are in a linked state at a distance of 5.8 morganids. A diheterozygous plant was crossed with a dwarf plant with pear-shaped fruits. What will the offspring be like?

Problem 63.

Problem 64.

Two lines of mice were crossed: in one of them, animals with curled hair of normal length, and in the other, with long and straight hair. The first generation hybrids had straight hair of normal length. In the analytical crossing of the first generation hybrids, the following were obtained: 11 mice with normal straight hair, 89 with normal crimped hair, 12 with long crimped hair, 88 with long straight hair. Locate genes on chromosomes.

* Problem 65to construct chromosome maps

Experiments have established

that the percentage of crossover between genes is equal to:

A) A – B = 1.2% B – C = 3.5% A – C = 4.7	B) C – N = 13% C – P = 3% P – N = 10% C – A = 15% N – A = 2%
B) P – G = 24% R – P =14% R – S = 8% S – P = 6%	D) A – F = 4% C – B = 7% A – C = 1% C – D = 3% D – F = 6% A – D = 2% A – B = 8%

Determine the position of genes on the chromosome.

Problems from the Unified State Exam demonstration materials

different years

Part A.

1. The diagram AABB x aABB illustrates the crossing:

1. monohybrid 2. polyhybrid

3. analyzing dihybrid

4. analyzing monohybrid

1. Indicate the genotype of the person, if according to the phenotype he is fair-haired and blue-eyed (recessive traits)

1. ААВВ 2. АаВв 3. аавв 4. Аавв

1. Homozygous dominant gray sheep die when switching to roughage, while heterozygous ones survive. Determine the genotype of a gray viable individual

1. Аа 2. АА 3. АаВв 4. АаВВ

1. In dogs, black coat color dominates over brown, short legs dominate over normal leg length. What is the genotype of a brown short-legged dog that is homozygous for leg length?

1. ааВв 2. ааВв 3. АаВв 4.ааВВ

1. In peas, the yellow color of the seeds dominates over the green, the smooth shape of the seeds dominates over the wrinkled one. Determine the genotype of a homozygous plant with yellow wrinkled seeds

1. AABB 2. aaBB 3. aaBB 4. AABB

6. What gametes do individuals with the aaBB genotype have?

1. aa 2. aaBB 3. BB 4. aB

1. An individual with the Aabv genotype produces gametes

1. Av, vv 2. Av, av 3. Aa, AA 4. Aa, vv

1. What genotype will the offspring in F 1 have when crossing tomato plants with genotypes AAbb and aaBB?

1. aaBB 2. AaBB 3. AaBB 4. AaBB

1. What is the probability of having tall children (recessive trait) from heterozygous parents of short stature?

1. 0% 2. 25% 3. 50% 4. 75%

1. When a monohybrid crossing of a heterozygous individual with a homozygous recessive individual occurs in their offspring, a phenotypic cleavage occurs in the ratio

1. 3: 1 2. 9: 3: 3: 1 3. 1: 1 4. 1: 2: 1

1. What percentage of night beauty plants with pink flowers can be expected from crossing plants with red and white flowers (incomplete dominance)?

1. 25% 2. 50% 3. 75% 4. 100%

1. What ratio of traits according to the phenotype is observed in the offspring during an analyzing cross, if the genotype of one of the parents is AaBb (characters are inherited independently of each other)?

1. 1:1:1:1 2. 1:1 3. 3:1 4. 1:2:1

1. What phenotype can be expected in the offspring of two guinea pigs with white fur (recessive trait)

1. 100% white

2. 25% white and 75% black

3. 50% white and 50% black

4. 75% white and 25% black

1. When crossing fruit flies with long wings (dominant trait), long-winged and short-winged offspring were obtained in a ratio of 3: 1. What are the genotypes of the parents?

1. BB and BB 2. BB and BB 3. BB and BB 4. BB and BB

1. Determine the genotypes of the parent pea plants if the crossing resulted in 50% of plants with yellow and 50% with green seeds (recessive trait)

1. AA and aa 2. Aa and Aa 3. AA and Aa 4. Aa and aa

1. When crossing two guinea pigs with black hair (dominant trait), offspring were obtained, of which 25% were individuals with white hair. What are the genotypes of the parents?

1. AA x aa 2. Aa x AA 3. Aa x Aa 4. AA x AA

1. A girl develops from an egg if chromosomes are found in the zygote during the process of fertilization

1. 44 autosomes + XX

2. 23 autosomes + X

3. 44 autosomes + XY

4. 23 autosomes + Y

1. Eye color in a person is determined by an autosomal gene, color blindness is a sex-linked recessive gene. Determine the genotype of a brown-eyed (dominant trait) woman with normal color vision, whose father is blue-eyed colorblind

1. AA X D X D 2. Aa X d X d 3. Aa X D X d 4. aa X D X d

1. Albinism is determined by a recessive autosomal gene, and hemophilia is determined by a sex-linked recessive gene. Indicate the genotype of the woman - albino, hemophiliac.

1. АаХ H Y or ААХ H Y 2. АаХ H Х H or АА Х H Х H

3. ааХ h Y 4. ааХ h Х h

1. A boy with hemophilia was born into a family of healthy parents. What are the genotypes of the parents?

1. X H X h and X h Y 2. X H X h and X H Y

3. X H X H and X H Y 4. X h X h and X H Y

Part C.

1. The absence of small molars in humans is inherited as a dominant autosomal trait. Determine the possible genotypes and phenotypes of parents and offspring, if one of the spouses has small molars, while the other does not have them and is heterozygous for this trait. What is

the likelihood of having children with this anomaly

3. When crossing a tomato with a purple stem (A) and red fruits (B) and a tomato with a green stem and red fruits, 722 plants with a purple stem and red fruits and 231 plants with a purple stem and yellow fruits were obtained. Make a diagram for solving the problem. Determine the genotypes of parents, offspring in the first generation and the ratio of genotypes and phenotypes in the offspring.

genotypes of parents, offspring and type of crossing. White color and smooth coat are recessive traits

5. In humans, the gene for brown eyes dominates over blue eyes (A), and the gene for color blindness is recessive (color blindness - d) and linked to the X chromosome. A brown-eyed woman with normal vision, whose father had blue eyes and suffered from color blindness, marries a blue-eyed man with normal vision. Make a diagram for solving the problem. Determine the genotypes of the parents and possible offspring, the likelihood of having color-blind children with brown eyes and their gender in this family.

6. Using the pedigree presented in the figure, establish the nature of inheritance of the trait highlighted in black (dominant or recessive, sex-linked or not), the genotypes of children in the first and second generation.

3. Autosomes – chromosomes on which males and females do not differ.

4. Gene interaction – the interconnected action of one, two or more pairs of genes that determine the development of the same trait.

5. Genetics – the science of heredity and variability.

6. Genotype – the sum of genes received by an organism from its parents.

7. Heterozygote(ʼʼheteroʼʼ=ʼʼdifferentʼʼ) – an organism with different alleles in the genotype (for example: Aa)

8. Hybrid generation – generation obtained from parents with different characteristics.

9. Hybrid – one organism from a hybrid generation.

10. Homozygote(ʼʼhomoʼʼ = ʼʼsameʼʼ) – an organism with the same alleles in the genotype (for example: AA or aa)

11. Dominant trait – predominant feature (sign that suppresses the others): A, B, C,...

12. Dominance – the simplest form of gene interaction according to the type “dominance - recessiveness”, established by G. Mendel.

13. Variability – the general property of all organisms to acquire new characteristics (within a species).

14. Co-dominance – a form of gene interaction in which heterozygotes exhibit both alleles (for example, inheritance of blood group 4 in humans: AB).

15. Complementarity – a form of gene interaction where one gene complements the action of another gene.

16. Locus – the location of the gene on the chromosome.

17. Mendel Gregor(Czech monk) – founder of genetics.

18. Morgan Thomas(American scientist) - creator of the chromosomal theory of heredity.

19. Heredity – the common property of all organisms to pass on their characteristics to their descendants.

20. Incomplete dominance – the case when a heterozygous offspring has an intermediate phenotype.

21. Sex chromosomes – chromosomes on which males and females have differences.

22. Polymeria – a form of gene interaction in which one trait is determined by several equivalent pairs of genes.

23. Recessive trait – suppressed trait (character that is suppressed by the dominant one): a, b, c, ...

24. Phenotype – the sum of external and internal characteristics of an organism.

25. Epistasis– a form of gene interaction in which one gene suppresses the action of another gene (for example, A>B or aa>B).

List of used literature

• Bagotsky S.V. Cool problems in genetics /magazine Biology for schoolchildren No. 4 – 2005.
• Bashurova T.I. Fabulous problems in genetics / Biology magazine: September 1, No. 8 - 2012.
• Gulyaev G.V. Problem book on genetics, M., Kolos, 1980.
• Zhdanov N.V. Solving problems when studying the topic “Population Genetics”. - Kirov, ped. inst., 1995.
• Problems in genetics for applicants to universities. –

ᴦ. Volgograd, Teacher, 1995.

• Kochergin B. N., Kochergina N. A. Problems in molecular biology and genetics, Minsk, Narodnaya Asveta, 1982.
• A short collection of genetic problems, Izhevsk, 1993.
• Methodological development for the student of the biological department of the Higher Medical School at Moscow State University Mendel's Laws, - M., 1981.
• Guidelines for self-preparation for practical classes in general genetics. - Perm, honey. inst. 1986.
• Murtazin G. M. Problems and exercises in general biology. – M., 1981.
• Orlova N. N. ʼʼ. Small workshop on general genetics / collection of problems. - Ed. Moscow State University, 1985.
• Collection of problems in biology / teaching aid for applicants to medical school. inst. - Kirov, 1998.
• Sokolovskaya B. Kh. One hundred problems in molecular biology and genetics. - M., 1981.
• Fridman M.V. Problems in genetics at the Moscow State University School Olympiad /magazine Biology for schoolchildren No. 2 - 2003.
• Shcheglov N.I. Collection of problems and exercises in genetics. - MP Ecoinvest, 1991.
• http://www.ege.edu.ru/
• http://www.fipi.ru/

Sources of illustrations:

1 option

1. The rule of uniformity of first-generation hybrids appears if the genotype of one of the parents is aabb, and the other:

Determine the genotype of the parent pea plants if their crossing resulted in 50% of plants with yellow and 50% with green seeds (recessive trait)

A. AA x aa

b. Aa x Aa

V. AA x Aa

Mr. Aa x aa

How many pairs of alternative traits do I study in a monohybrid cross?

Can a daughter be born with hemophilia if her father is a hemophiliac?

A. Maybe, since the hemophilia gene is located on the Y chromosome

b. It cannot, since the hemophilia gene is located in somatic cells

V. She can’t because she is heterozygous for the X chromosome.

d. Maybe if the mother is a carrier of the hemophilia gene.

Homozygous dominant gray sheep die when switching to roughage, while heterozygous ones survive. Determine the genotype of a gray viable individual:

A girl develops from an egg if, during the process of fertilization, the following chromosomes are found in the zygote:

a.44 autosomes + XY

b.23 autosomes +X

v.44 autosoma + XX

d.23 autosomes + U

G. Mendel named the predominant characteristic of one of the parents:

A. recessive

b. Dominant

V. Homozygonous

d. heterozygous

If genes responsible for the development of several traits are located on one chromosome, then the law appears:

A. Splits

b. Chained inheritance

V. Incomplete dominance

d. Independent inheritance

What information does a gene carry?

A. protein molecule synthesis,

b. body education,

V. organ formation

Where is the gene located?

A. cytoplasm,

b. nuclear juice,

V. chromosome

11. What is the set of chromosomes in somatic cells

A. haploid b. diploid

V. triode

12. Phases of meiosis:

A. amitosis, mitosis, interphase

b. prophase, metaphase, anaphase, telophase

V. chromosome, centriole, centromere

13. The science of heredity

A) cytology B) selection

C) genetics D) biology

14. Formula of a homozygous individual

A) aa B) aA C) Aa

15. In which row are the formulas of individuals written using only homozygous traits?

A) Aa; BB; Vv

B) AA; Vv; BB

B) AA; BB; bb

D) Aa; BB; bb

16. How parents are designated

2. Complete the sentences:

The set of genes of an organism is _____________. Crossing forms that differ from each other in one pair of characteristics is ____________. Crossings carried out to determine the genotype of an organism are ___________. The form of inheritance of traits in first-generation hybrids, when a recessive trait is partially manifested in the presence of a dominant gene, is __________________. Individuals in whose offspring splitting is detected are _____________.

3. Task:

Determine the genotypes of the parents, possible genotypes and phenotypes of children born from the marriage of a homozygous curly-haired man with thick lips to a heterozygous curly-haired woman with thin lips. Curly hair and thick lips are dominant characteristics.

Option 2

Part 1. Choose one correct answer:

1. How many types of gametes are formed in diheterozygous pea plants during dihybrid crossing?

2. Paired genes located on homologous chromosomes and controlling the manifestation of the same trait are called:

A. Allelic

b. Dominant

V. Recessive

interlocked

3. In dogs, black fur (A) dominates over brown coloring (a), and short legs (B) dominate over normal leg length (c). select the genotype of a black short-legged dog, heterozygous only for leg length:

4. When crossing heterozygous tomato plants with red and round fruits with individuals recessive for both traits (red A and round B are dominant traits), offspring will appear with genotypes AaBb, aaBb, Aabv, aabv in the ratio:

5. A boy develops from an egg if, during the process of fertilization, the following chromosomes are found in the zygote:

a.44 autosomes + XY

b.23 autosomes +X

v.44 autosoma + XX

d.23 autosomes + U

6. G. Mendel named the suppressed trait of one of the parents:

A. Recessive

b. Dominant

V. Homozygonous

d. Heterozygous

7. When crossing a heterozygote with a homozygote, the proportion of homozygotes in the offspring will be:

8.Which signs are paired:

A. yellow and green;

b. yellow color and smooth surface;

V. smooth and wrinkled surface

9. What method of pollination was used by G. Mendel to obtain second-generation hybrids a. cross,

b. self-pollination,

V. artificial pollination

10. Which is more subject to change under the influence of environmental conditions?

A. genotype,

b. phenotype

11. What is the set of chromosomes in germ cells?

A. haploid b. diploid

V. triode

12. Biological essence of meiosis

A) reducing the number of chromosomes by half

B) formation of germ cells

B) formation of diploid gametes

13. The Science of Variation

A) cytology B) selection

C) genetics D) biology

14. Formula of a heterozygous individual

A) aa B) AA C) Aa

15. In which row are the formulas of individuals written with only heterozygous characteristics?

A) Aa; vV; Vv

B) AA; Vv; BB

B) AA; BB; bb

D) Aa; BB; bb

16. How are hybrids of different generations designated (row)

2. Complete the sentences:

The elementary unit of heredity, represented by a segment of a DNA molecule, is ____. The pair of genes that determine contrasting traits is _________. The trait that appears in first-generation hybrids when crossing pure lines is __________________. The normal set of sex chromosomes in a man is _____________. Crossing forms that differ from each other in two pairs of characteristics is called ____________.

3. Task:

Determine the genotypes of the parents, possible genotypes and phenotypes of children born from the marriage of a fair-haired, blue-eyed girl and a diheterozygous brown-eyed, dark-haired man. If dark hair color dominates light, and brown eyes dominate blue.

Domination manifests itself in cases where one allele of a gene completely hides the presence of another allele. However, most often the presence of a recessive allele has some effect and usually one encounters varying degrees of incomplete dominance.

Complete Domination . Using the example of G. Mendel's experiments with peas, it is clear that one gene can completely suppress the manifestation of another allelic gene. Incomplete dominance. With incomplete dominance, the trait appears in the first generation intermediate between the parental forms. If you mate long-eared Karakul sheep with earless ones, then in F1 all the offspring will be short-eared. The splitting in F2 by phenotype and genotype coincides (1:2:1).

Codominance . Both allelic genes appear in the phenotype, revealing neither dominance nor recessivity among themselves. In humans, the ABO blood systems are known, which determine erythrocyte antigens. Alleles A and B interact according to the type of codominance. From 1940 to 1970, 12 genetic systems of blood groups were discovered in cattle. They distinguish more than 100 blood antigens, defining 369 phenogroups, which can amount to about two trillion different combinations - serological types. Phenogroup- a group of antigens (sometimes one antigen), which are the phenotypic expression of a set of individual genes of one locus. Blood groups, which are based on the individual characteristics of the antigenic properties of red blood cells, are hereditary and do not change throughout the life of the animal. They are inherited singly or complexly and therefore can serve as a convenient genetic model in solving many theoretical and practical issues of selection, since the overwhelming number of known allelic erythocyte factors are inherited according to the type of codominance.

Overdominance e. It is characterized by the fact that in heterozygous individuals the trait is more pronounced than in homozygous dominant individuals, that is, the hybrid is superior to both parents in the development of the trait. This phenomenon is called heterozasome(Aa>AA and a a). A clear example of overdominance is human sickle-shaped anemia. SS homozygotes have some of their red blood cells in the shape of a sickle and arrowhead, and their red blood cell oxygen transport is impaired. People suffer from acute anemia and usually die at an early age. Heterozygotes Ss are resistant to tropical malaria, homozygotes ss develop tropical malaria.

Multiple allelism. The phenomenon in which basically the interaction of two allelic genes, each of which can change as a result of mutation and a new allelic gene arises, is called " multiple allelism". In humans, an example of multiple allelism is the ABO blood system, which has 3 allelic genes (A, B, O) and, accordingly, 6 genotypes and 4 phenotypes. In rabbits, the following alleles have been identified that affect hair color: C - black, cсh - chinchilla, ch - Himalayan, ca - albino. Alleles are presented in descending order of dominance (C>cch>ch>ca). Allele C is dominant over all subsequent ones, ca is recessive to all previous ones.

Pleiotropic effect of the gene . A gene can influence the development of two or more traits, that is, multiple effects of the gene are observed. This type of interaction was discovered when breeding gray (Shirazi) and black (Arabi) Karakul sheep. Lambs homozygous for the dominant allele of the C gene, which determines the gray color (Shirazi). when switching to pasture they die due to underdevelopment of the parasympathetic nervous system of the rumen. This is due to the action of two dominant genes that have double (pleiotropic) action: cause gray coloration and in the homozygous state - a defect in the nervous system.

Lethal and semi-legal genes . Genes cause complex physiological changes during the development of an organism. They can reduce the vitality of the body, even to the point of death. One of the reasons that changes the splitting in a ratio of 3:1. is the different viability of homozygotes in F2. In the 20th century facts were discovered when a 2:1 phenotype split occurred. Thus, when studying the inheritance of color in yellow and black mice, a split in color into 2 parts yellow and 1 part black mice was observed. In this case, some of the yellow mice died during the embryonic period. The same gene in a dominant heterozygous state caused the yellow coloration of mice, and in a homozygous state it showed its lethal effect. The black color gene is allelic and recessive. In the 30s of the XX century. A new coloration was discovered in the silver-black fox, called platinum. When platinum foxes were crossed with each other, the individuals had both platinum and silver-black coloring in a 2:1 ratio. When conducting an analytical cross, it became clear that the platinum color gene is dominant. It has been suggested that homozygous platinum foxes (AA) die during the embryonic period. Autopsies of pregnant females confirmed this assumption. Recessive lethal genes act in homozygous state, and dominant ones - and in heterozygous. If a gene does not cause the death of the organism, but significantly reduces viability, then it is called semi-lethal. Lethal and semi-legal genes most often recessive.

Lethal genes cause the death of the organism in the embryonic or postembryonic period. For example, recessive legal genes cause the absence of fur in newborn calves, rabbits and animals of other species. Soon after birth, these animals die.

Semi-legal genes can cause deformities in animals: shortening of the axial skeleton; deformation of the head and limbs; violation of the physiological functions of the body. Breeding animals with lethal and semi-lethal genes must be culled. It is especially necessary to check breeding sires from whom a large number of offspring are obtained through artificial insemination.

Complete dominance. Using the example of G. Mendel's experiments with peas, it is clear that one gene can completely suppress the manifestation of another allelic gene.
Incomplete dominance. With incomplete dominance, the trait also appears in the first generation intermediate between the parental forms. If you mate long-eared Karakul sheep with earless ones, then in F1 all the offspring will be short-eared. The splitting in F2 by phenotype and genotype coincides (1:2:1).
Codominance. Both allelic genes appear in the phenotype, revealing neither dominance nor recessivity among themselves. In humans, the ABO blood systems are known, which determine erythrocyte antigens. Alleles A and B interact according to the type of codominance.
From 1940 to 1970, 12 genetic systems of blood groups were discovered in cattle. They distinguish more than 100 blood antigens, defining 369 phenogroups, which can amount to about two trillion different combinations - serological types. Phenogroup- a group of antigens (sometimes one antigen), which are the phenotypic expression of a set of individual genes of one locus. Blood groups, which are based on the individual characteristics of the antigenic properties of red blood cells, are hereditary and do not change throughout the life of the animal. They are inherited singly or complexly and therefore can serve as a convenient genetic model in solving many theoretical and practical issues of selection, since the overwhelming number of known allelic erythocyte factors are inherited according to the type of codominance.
Overdominance. It is characterized by the fact that in heterozygous individuals the trait is more pronounced than in homozygous dominant individuals, that is, the hybrid is superior to both parents in the development of the trait. This phenomenon is called heterozas (Aa>AA and aa). A clear example of overdominance is human sickle-shaped anemia. SS homozygotes have some of their red blood cells in the shape of a sickle and arrowhead, and their red blood cell oxygen transport is impaired. People suffer from acute anemia and usually die at an early age. Heterozygotes Ss are resistant to tropical malaria, homozygotes ss develop tropical malaria.
Multiple allelism. We mainly considered the interaction of two allelic genes, each of which can change as a result of mutation and a new allelic gene arises. This phenomenon is called "multiple allelism." In humans, an example of multiple allelism is the ABO blood system, which has 3 allelic genes (A, B, O) and, accordingly, 6 genotypes and 4 phenotypes.
The following alleles have been identified in rabbits that affect hair color: C - black, cсh - chinchilla, ch - Himalayan, ca - albino. Alleles are presented in descending order of dominance (C>cch>ch>ca). Allele C is dominant over all subsequent ones, ca is recessive to all previous ones (Fig. 2.5).

Pleiotropic effect of the gene. A gene can influence the development of two or more traits, that is, multiple effects of the gene are observed. This type of interaction was discovered when breeding gray (Shirazi) and black (Arabi) Karakul sheep. Lambs homozygous for the dominant allele of the C gene, which determines the gray color (Shirazi). when switching to pasture they die due to underdevelopment of the parasympathetic nervous system of the rumen. This is due to the action of two dominant genes, which have a double (pleiotropic) effect: they cause gray coloration and, in the homozygous state, a defect in the nervous system.
Academician D.K. Belyaev and his colleagues found that in minks some mutations associated with changes in hair color are recessive, and due to a pleiotropic effect, the fertility and viability of animals are reduced.
Lethal and semi-legal genes. Genes cause complex physiological changes during the development of an organism. They can reduce the vitality of the body, even to the point of death.
One of the reasons that changes the splitting in a ratio of 3:1. is the different viability of homozygotes in F2. In the 20th century facts were discovered when a 2:1 phenotype split occurred. Thus, when studying the inheritance of color in yellow and black mice, a split in color into 2 parts yellow and 1 part black mice was observed. In this case, some of the yellow mice died during the embryonic period. The same gene in a dominant heterozygous state caused the yellow coloration of mice, and in a homozygous state it showed its lethal effect. The black color gene is allelic and recessive.
In the 30s of the XX century. A new coloration was discovered in the silver-black fox, called platinum. When platinum foxes were crossed with each other, the individuals had both platinum and silver-black coloring in a 2:1 ratio. When conducting an analytical cross, it became clear that the platinum color gene is dominant. It has been suggested that homozygous platinum foxes (AA) die during the embryonic period. Autopsies of pregnant females confirmed this assumption.
Recessive lethal genes act in a homozygous state, and dominant ones also act in a heterozygous state. If a gene does not cause the death of the organism, but significantly reduces viability, then it is called semi-lethal.
Lethal and semi-legal genes are most often recessive. Lethal genes cause the death of the organism in the embryonic or postembryonic period. For example, recessive legal genes cause the absence of fur in newborn calves, rabbits and animals of other species. Soon after birth, these animals die.
Semi-legal genes can cause deformities in animals: shortening of the axial skeleton; deformation of the head and limbs; violation of the physiological functions of the body. Breeding animals with lethal and semi-lethal genes must be culled. It is especially necessary to check breeding sires from whom a large number of offspring are obtained through artificial insemination.
Legal genes can spread freely from one country to another. Thus, the breeding bull of the Dutch breed Prince Adolf, a carrier of a genetic anomaly, was brought to Sweden from the Netherlands in 1902. 26 years later it became known that the bull is a carrier of the lethal recessive gene for hairless calves. His daughters, sons and grandsons were widely used for breeding purposes, and within a relatively short time many of the animals were related to Prince Adolf. In some herds, about 6% of calves were born without hair and died within minutes of birth.
Recently, reports have appeared in foreign and domestic literature about genetic anomalies (defects) causing enormous economic damage to livestock breeding (P. D. Smith, L. F. Novikova). So, for example, defects BLAD (Bovine Leukocyte Adhesion Deficiency), or adhesion (clumping) of leukocytes in cattle and CVM (Complex Vertebral Malformation), or complex deformity of the spine, have a recessive type of inheritance and are not expressed in the heterozygous state (Fig. 2.6) . These genetic defects have become widespread in the line of Holstein cattle Montvik Chieftain 95679, which is widely used in the Russian Federation. One of the most famous bulls of this line, Osbordale Ivanhoe 1189870, was a carrier of the genetic defect B LAD. and his grandson Carlin-M Ivanhoe Bell 1667366 is a carrier of both genetic defects BLAD and CVM.

On average, 2-5% of newborn animals of many species have hereditary anomalies. Lethal and semi-legal genes are one of the causes of embryonic mortality and congenital anomalies. Several dozen such genes have been identified for each type of farm animal, and an international classification of anomalies has been given. The hereditary nature of stillbirths, miscarriages, and deformities is evidenced by the fact that their percentage increases significantly with inbreeding.
The most common hereditary anomalies in cattle are: pug-like; muscle contracture; absence of fore and hind limbs; hydrops of the fetus and brain; skin defects: hairlessness; shortening of the jaw; umbilical hernia, etc.
Summarizing the data of different authors, we can say that in cattle there are more than 40 homozygous lethalities, deformities and karyotype anomalies - hereditary marriages. 23 congenital defects were identified that affect the reproductive function and fertility of cows.
33 genetic abnormalities have been described in pigs. The most common are: cerebral hernia; paralysis of the hind limbs; absence of anus; cleft palate; thick-legged; curvature and rigidity of the limbs; dropsy of the brain; hemophilia.
In sheep, the most pronounced craniofacial defects are: shortening or absence of the lower jaw; hair loss, baldness; dwarfism; cleft palate, etc. A total of 43 anomalies.
The International List of Legal Defects includes 45 anomalies in chickens; 6 - in turkeys; 3 - in ducks; Of the hereditary anomalies, 10 are in horses.
The hereditary origin of the anomaly is indicated by the following facts: the correspondence of the detected anomaly to the description of the genetic defect, the appearance of the anomaly as a result of inbreeding, the manifestation of similar anomalies in lateral relatives (sibs and half-sibs), relatives of the mother or father.
All cases of manifestation of hereditary anomalies must be recorded in the cards of breeding animals so that genetic analysis can be carried out in the future. In this situation, pedigree and objective breeding records play an important role. Data collection for assessing the genetic well-being of breeding animals and the presence of lethal and semi-legal genes should be carried out at breeding enterprises and stations for artificial insemination of farm animals.