Complete dominance. On the example of G. Mendel's experiments with peas, it can be seen that one gene can completely suppress the manifestation of another allelic gene.
incomplete dominance. With incomplete dominance, the trait in the first generation also manifests itself intermediately between the parental forms. If long-eared Karakul sheep are mated with earless ones, then in F1 all offspring will be short-eared. Cleavage in F2 by phenotype and genotype is the same (1:2:1).
Codominance. In the phenotype, both allelic genes are manifested, showing neither dominance nor recessiveness among themselves. In humans, ABO blood systems are known, which determine erythrocyte antigens. Alleles A and B interact by 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 that define 369 phenogroups, which can be about two trillion different combinations - serological types. Phenogroup- a group of antigens (sometimes one antigen), which are the phenotypic expression of the totality of individual genes of one locus. Blood groups based on individual characteristics antigenic properties of erythrocytes are hereditarily determined 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 vast majority of known allelic erythocyte factors are inherited by the type of codominance.
Overdominance. It is characterized by the fact that in heterozygous individuals the trait is stronger than in homozygous dominant ones, that is, the hybrid surpasses both parents in the development of the trait. This phenomenon is called heterozasom (Aa> AA and a a). illustrative example overdominance - sickle-shaped [with an exact anemia of a person. Homozygotes of SS have part of the erythrocytes in the form of a sickle and arrowhead, they have impaired oxygen transport by erythrocytes. People suffer from an acute form of anemia and usually die in early age. Heterozygotes Ss are resistant to tropical malaria, homozygotes ss get sick with 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.
In rabbits, the following alleles have been established that affect the color of the hairline: C - black, cch - chinchilla, ch - Himalayan, ca - albino. Alleles are presented in descending order of dominance (C>cch>ch>ca). Allele C dominates all subsequent ones, ca is recessive to all previous ones (Fig. 2.5).
Pleiotropic action of the gene. A gene can influence the development of two or more traits, that is, there is a multiple effect of the gene. This type of interaction was found when breeding Karakul sheep of gray color (Shirazi) and black (Arabi). 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 scar. This is due to the action of two dominant genes that have a double (pleiotropic) effect: they cause a gray color and, in the homozygous state, a defect in the nervous system.
Academician D.K. Belyaev and his coworkers found that some mutations in minks associated with a change in the color of the hairline are recessive, and due to the 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 viability of the body up to death.
One of the reasons for changing the splitting ratio is 3:1. is the different viability of homozygotes in F2. In the XX century. facts were discovered when a 2:1 splitting occurred in the phenotype. So, when studying the inheritance of color in yellow and black mice, splitting in color into 2 parts of yellow and 1 part of black mice was observed. At the same time, part of the yellow mice died in the embryonic period. The same gene in the dominant heterozygous state caused the yellow coloration of mice, and in the homozygous state it showed its lethal effect. The black 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 crossing platinum foxes between themselves, the individuals had both platinum and silver-black color in a ratio of 2:1. When carrying out analyzing crosses, it became clear that the platinum color gene is dominant. It has been suggested that homozygous platinum foxes (AA) die in the embryonic period. Autopsy of pregnant females confirmed this assumption.
Recessive lethal genes act in the homozygous state, and dominant ones also in the heterozygous state. If the gene does not cause the death of the organism, but significantly reduces the 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 coat in newborn calves, rabbits and animals of other species. Shortly after birth, these animals die.
Semi-legal genes can cause deformities in animals: shortening of the axial skeleton; deformation of the head, limbs; violation of the physiological functions of the body. Breeding animals with lethal and semi-lethal genes must be culled. Especially carefully it is necessary to check breeding producers, from whom, during artificial insemination, big number descendants.
Legal genes can spread freely from one country to another. Thus, a breeding bull of the Dutch breed Prince Adolf, a carrier of a genetic anomaly, was brought to Sweden from the Netherlands in 1902. After 26 years, it became known that the bull is a carrier of a lethal recessive gene for hairless calves. His daughters, sons and grandsons were widely used for tribal purposes, and through relatively a short time many animals were related to Prince Adolf. In some herds, about 6% of calves were born without wool and died a few minutes after birth.
AT recent times in foreign and domestic literature, there were reports of genetic anomalies (defects) causing enormous economic damage to livestock breeding (P. D. Smith, L. F. Novikova). For example, defects in 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 a 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 Russian Federation. One of the most famous bulls of this line, Osbordale Ivanhoe 1189870, was a carrier of the B LAD genetic defect. 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 dozens of such genes have been identified for each type of farm animal, and an international classification of anomalies has been given. The hereditary conditionality of stillbirths, miscarriages, 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; dropsy 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 lethals, deformities and anomalies of the karyotype - a hereditary marriage. 23 congenital defects affecting the reproductive function and fertility of cows were identified.
33 genetic abnormalities have been described in pigs. The most common are: cerebral hernia; paralysis of the hind limbs; absence of an anus; cleft palate; thick-footedness; curvature and rigidity of the limbs; dropsy of the brain; hemophilia.
In sheep, craniofacial defects are most pronounced: shortening or absence of mandible; 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 hereditary anomalies 10 in horses.
The following facts indicate the hereditary origin of the anomaly: 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 such anomalies in lateral relatives (siblings 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 further genetic analysis can be carried out. 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, stations for artificial insemination of farm animals.
1 option
1. The rule of uniformity of hybrids of the first generation will appear if the genotype of one of the parents is aavb, and the other:
Determine the genotype of the parent pea plants if, when they were crossed, 50% of plants with yellow and 50% with green seeds were formed (recessive trait)
a. AA x aa
b. Aa x Aa
in. AA x Aa
Mr. Aa x aa
How many pairs of alternative traits do I study in a monohybrid cross?
Can a daughter with hemophilia be born if, if her father is hemophilic?
a. Maybe because the hemophilia gene is located on the Y chromosome
b. It cannot, because the hemophilia gene is located in somatic cells
in. Can't because she's 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 zygote contains chromosomes:
a.44 autosomes + XY
b.23 autosomes +X
c.44 autosomes + XX
d.23 autosomes + Y
G. Mendel called the predominant feature of one of the parents:
a. recessive
b. Dominant
in. homozygous
d. heterozygous
If the genes responsible for the development of several traits are located on the same chromosome, then the law manifests itself:
a. Cleavage
b. Linked inheritance
in. incomplete dominance
d. Independent Succession
What information does a gene carry?
a. protein synthesis,
b. body formation,
in. organ formation
Where is the gene located
a. cytoplasm,
b. nuclear juice,
in. chromosome
11. What is the set of chromosomes in somatic cells
a. haploid b. diploid
in. triode
12. Phases of meiosis:
a. amitosis, mitosis, interphase
b. prophase, metaphase, anaphase, telophase
in. 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 only with homozygous traits
A) aa BB; Vv
B) AA; Vv; BB
B) AA; BB; centuries
D) Aa; BB; centuries
16. How parents are designated
2. Complete the sentences:
The totality of an organism's genes is _________. Crossing forms that differ from each other in one pair of characters - ____________. Crossing carried out to determine the genotype of an organism is ___________. The form of inheritance of traits in hybrids of the first generation, when a recessive trait is partially manifested in the presence of a dominant gene, is __________________. Individuals in the offspring of which splitting is found 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 traits.
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
in. recessive
d. linked
3. In dogs, black coat (A) dominates over brown color (a), and short-legged (B) dominates over normal leg length (c). select the genotype of a black short-legged dog that is heterozygous for leg length only:
4. When heterozygous tomato plants with red and round fruits are crossed with individuals that are recessive in both traits (red A and round B are dominant traits), offspring with genotypes AaBb, aaBb, Aavb, aavb will appear in the ratio:
5. A boy develops from an egg, if during the process of fertilization there are chromosomes in the zygote:
a.44 autosomes + XY
b.23 autosomes +X
c.44 autosomes + XX
d.23 autosomes + Y
6. The suppressed sign of one of the parents G. Mendel called:
a. recessive
b. Dominant
in. homozygous
d. Heterozygous
7. When crossing a heterozygote with a homozygote, the proportion of homozygotes in the offspring will be:
8. What signs are paired:
a. yellow and green;
b. yellow and smooth surface
in. smooth and wrinkled surface
9. What method of pollination did G. Mendel use to obtain hybrids of the second generation a. cross,
b. self-pollination,
in. artificial pollination
10. What is more exposed to changes under the influence of environmental conditions
a. genotype,
b. phenotype
11. What is the set of chromosomes in germ cells
a. haploid b. diploid
in. triode
12. Biological entity meiosis
A) halving the number of chromosomes
B) the formation of germ cells
C) the formation of diploid gametes
13. The Science of Change
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 only with heterozygous traits
A) aa vV; Vv
B) AA; Vv; BB
B) AA; BB; centuries
D) Aa; BB; centuries
16. How hybrids of different generations are designated (row)
2. Complete the sentences:
The elementary unit of heredity, represented by a segment of the DNA molecule, is ____. A pair of genes that determines contrasting traits is _________. The trait that appears in hybrids of the first generation when crossing pure lines is __________________. Normally, the 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 over light, and brown eyes over blue.
Municipal treasury educational institution
average comprehensive school № 2
with in-depth study of individual subjects
Vostochny village, Omutninsky district, Kirov region
(manual for pupils 9 - Grade 11)
Vostochny - 2013
Maslak Ekaterina Nikolaevna -
biology teacher of the highest category
MKOU secondary school No. 2 with UIOP
Vostochny, Omutninsky District
Dear friend!
You have a collection of problems in genetics in your hands.
You are offered different types tasks:
Try to solve them
and you will make sure
that genetics is a very interesting science!
Wish you luck!
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| page 14 |
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| Combined tasks | page 16 |
| page 18 |
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| page 21 |
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| Tasks on the topic "Linked inheritance (crossing over)" | page 22 |
| different years | page 23 |
| Concise Dictionary of Genetic Terms | page 28 |
| page 30 |
Preparation for solving problems in genetics
Crossword "Genetic terms"
9 10
5 13
12 15
The sum of external and internal signs of the organism
Location of a gene on a chromosome
General property all organisms acquire new traits within a species
An organism with the same alleles in the genotype
The science of heredity and variability
An organism with different alleles in the genotype
Objects with which T. Morgan conducted his experiments
Genes providing the development of alternative traits
The amount of genes received by an organism from its parents
Founder of genetics
The common property of all organisms to pass on their traits to their descendants
One organism from a hybrid generation
Sign that suppresses others
Suppressed symptom
Chromosomes on which males and females do not differ.
Tasks to prepare for solving genetic problems
Task 1. Correlate.
Task 2. How many allelic pairs are in the following genotypes?
AaVv
AaVvssDd
AaddCcDdee
Task 3. How many dominant genes are there in genotypes?
aaVVSs
AAvvSSDDee
AaBbccDdEe
Task 4. How many heterozygous alleles are there in genotypes?
aavvss
AAVvss
AABvSSddEe
Task 5. Will a dominant or recessive trait be manifested in individuals with this genotype?
AAVvss
aaBvSsDDEe
aaBbccDdee
Tasks on the topic "Monohybrid crossing"
Task 1.
Task 2.
In guinea pigs, black coat color is dominant over white. We crossed two heterozygous males and a female. What will be the first generation hybrids?
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 normal growth and 50% short?
* Task 7.
When crossing two white pumpkins in the first generation, ¾ of the plants were white and ¼ were yellow. What are the genotypes of the parents if white is dominant over yellow?
Task 8.
Task 9.
Task 10.
The Firebird has a bright yellow plumage, the Blue Bird is blue. When the Firebird was crossed with the Blue Bird, blue chicks hatched. What trait is dominant? What are the genotypes of parents and offspring?
Task 11.
Task 12. "The Tale of Dragons"
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 - in the offspring, there are approximately equal numbers of fire-breathing and non-fire-breathing dragons.
4. Non-fire-breathing male and fire-breathing female - all offspring are non-fire-breathing.
Assuming that the trait is determined by the autosomal gene, establish the dominant allele and write down the genotypes of the parents.
Tasks on the topic "Incomplete dominance"
Task 13.
When purebred white chickens are crossed, the offspring is white, and when black chickens are crossed, they are black. The offspring from a white and black individual turns out to be motley. What kind of plumage will the descendants of a white rooster and a motley hen have?
Task 14.
these varieties with each other produce pink berries. What offspring will arise when hybrids with pink berries are crossed?
Tasks on the topic "Di- and poly-hybrid crossing"
Task 15.
A blue-eyed right-handed young man (his father was left-handed), married a brown-eyed left-hander (all her relatives are brown-eyed). What children will possibly be from this marriage, if brown eyes and right-handedness are dominant signs?
Task 16.
Rabbits were crossed: a homozygous female with normal hair and hanging ears and a homozygous male with long hair and erect ears. What will be the hybrids of the first generation, if the usual coat and erect ears are dominant characters?
Task 17.
Task 18.
In a figured pumpkin, the white color of the fruit dominates over the yellow, the disc-shaped shape dominates over the spherical one. What hybrids will look like from crossing a homozygous yellow spherical pumpkin and a yellow discoid (heterozygous for the second allele).
Task 19.
In tomatoes, the red color of the fruit dominates over the yellow,
normal growth - over dwarfish. What will be the hybrids from crossing homozygous yellow tomatoes of normal growth and yellow dwarfs?
* Task 20.
What are the genotypes of the parent plants if, when crossing red tomatoes (dominant trait) pear-shaped (recessive trait) with yellow spherical ones, it turned out: 25% red spherical, 25% red pear-shaped, 25% yellow spherical, 25% yellow pear-shaped?
Task 21.
recessive r. What will be the first generation phenotype when a homozygous white shag unicorn is crossed with a homozygous yellow trotter? What offspring and in what proportions will be obtained by crossing two individuals of the first generation?
Task 22
Imagine that you are a consultant for a small company called "Cocktail", which literally means "cock's tail" in English. The company breeds exotic breeds of roosters for the sake of tail feathers, which owners of hat shops around the world are willing to buy. The length of the feathers is determined by the gene A (long) and a (short), color: B - black, c - 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 of which are entered into the computer. Next year, an increased demand for hats with long black narrow feathers is expected. What crosses should be carried out in order to obtain the maximum number of birds with fashionable feathers in the offspring? It is not worth crossing pairs with exactly the same genotypes and phenotypes.
Tasks on the topic "Inheritance of blood groups"
Task 23.
What blood types can children have if both parents have 4 blood types?
Task 24.
Is it possible to transfuse blood to a child from a mother if her blood type is AB, and the father's is O?
Task 25.
The boy has blood group 4, and his sister has blood type 1. What are their parents' blood types?
* Task 26.
Two boys (X and Y) were mixed up in the maternity hospital. X has the first blood type, Y has the second. Parents of one of them with 1 and 4 blood groups, and the other with 1 and 3 blood groups. Who is whose son?
Task 27.
Task 28.
The miller died in the village. Burying my father
The inheritance was divided by three young brothers:
The older brother took the mill, the second tidied up the donkey,
And the cat went to the youngest - the cat was taken by the younger brother.
Task 29.
The Thumb Boy has an AB blood type, his mother has an AO blood type. What blood type can a father have?
Tasks on the topic "Sex-linked inheritance"
Task 30.
What kind of vision can children have from the marriage of a man and a woman who normally distinguish colors, if it is known that their fathers suffered from color blindness?
Task 31.
Can the children of a man with hemophilia and a woman without anomalies (whose father had hemophilia) be healthy?
Task 32.
Task 33.
* Problem 34.
In healthy relatives to hemophilia, the husband and wife have
A son with hemophilia who has a healthy daughter
A healthy daughter who has 2 sons: one is sick with hemophilia and the other is healthy,
A healthy daughter with five healthy sons
What are the genotypes of this husband and wife?
Problem 35 .
Task 36.
Problem 37.
the likelihood that they would have a sweet tooth? Solve two versions of the problem: dad likes sweets and does not like.
Problem 38.
The Ryaba hen can lay golden and simple eggs. The recessive gene for golden eggs is located on the X chromosome. What should be the genotypes of Hens and Roosters so that all their Hens Ryaba lay golden eggs?
Problem 39. "Will the wedding of Prince Uno be upset?"
The only one crown prince Uno is about to marry the beautiful Princess Beatrice. Uno's parents learned that Beatrice's family had cases of hemophilia. Beatrice has no siblings. Aunt Beatrice has two sons - healthy strong men. Uncle Beatrice disappears hunting all day and feels great. The second uncle died as a boy from blood loss caused by a deep scratch. Uncles, aunt and mother Beatrice are children of the same parents. What is the probability that the disease can be transmitted through Beatrice to the royal family of her fiancé
Task 40. "Royal Dynasties"
Let's assume that Emperor Alexander Ι had a rare mutation on the Y chromosome. Could this mutation have: a) Ivan the Terrible
b) Petra Ι
c) Catherine ΙΙ
d) Nicholas ΙΙ?
Problem 41 . Leafing through the novel "War and Peace"
Suppose that Prince Nikolai Andreevich Bolkonsky had a rare mutation in the X chromosome. Pierre Bezukhov had the same mutation. What is the probability that this mutation could be in: a) Natasha Rostova
b) the son of Natasha Rostova
c) son of Nikolai Rostov
Combined tasks
Task 42.
parents from crossing a heterozygous komologo roan bull with a white horned cow.
Task 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 birth of the next child brown-eyed with 1 blood group.
Problem 45 .
A man with blue eyes and normal vision married a woman with brown eyes and normal vision (all her relatives had brown eyes, and her brother was colorblind). What are the children of this marriage?
Task 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.
Task 47.
A man suffering from color blindness and deafness married a woman with good hearing and normal vision. They had a son who was deaf and colorblind, and a daughter with good hearing and colorblindness. Is it possible for this family to have a daughter with both anomalies if deafness is an autosomal recessive trait?
Tasks 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 pea-shaped crest, individuals with a simple crest are recessive for both alleles. What will be the offspring when two heterozygotes are crossed?
Problem 49 .
The brown color of mink fur is due to the interaction of dominant alleles. Homozygosity for recessive alleles of one or two of these genes gives platinum coloration. What will be the hybrids from crossing two heterozygotes?
* Task 50 .
In alfalfa, the inheritance of flower color is the result of a 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 were with green flowers, in the second generation splitting 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 the 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 black (because it does not affect the distribution of the pigment). What will be the offspring from crossing two heterozygotes?
* Task 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 give a white color. When crossing black-grained oats, the offspring showed a split: 12 black-grained: 3 gray-grained: 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 skin color is darker, the more dominant genes in the genotype: if 4 dominant genes - the skin is black, if 3 - dark, if 2 - swarthy, if 1 - light, if all genes are in recessive condition - white. A black woman married a white-skinned man. What can 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 polymeric genes, while winterness is controlled by their recessive alleles. What will be the offspring when two heterozygotes are crossed?
Problem 55.
Birds Talkers are smart and quick-witted. The tufts on the head are white and red (the red color is inherited by two pairs of genes). Two white-tufted birds interbreed, and they hatch a chick with a red tuft 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 an ordinary 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 ordinary cores? What are the genotypes of the parents?
Problem 57. "Dispute between Bender and Panikovsky"
Two neighbors argued: how is color inherited in budgerigars? Bender believes that the color of parrots is determined by one gene that has 3 alleles: C about - recessive in relation to the other two, C g and c codominant Therefore, in parrots with genotype C o C o - white color, C g C g and C g C o - blue, C g C g and C g C o - yellow and C g - green color. And Panikovsky believes that the color is formed under the action of two interacting genes A and B. Therefore, parrots with the A * B * genotype are green, A * cc are blue, aaB * are yellow, aavv are white.
They made 3 genealogies:
1. P : Z x B 2. P : Z x Z 3. P : W x B
F1 : Z, B F1 : B F1 : G, F, G, G, F, F, F, G, F
Which genealogies could be compiled by Bender, which ones by Panikovsky?
Tasks on the topic "Analyzing Crossing"
Problem 58.
colors, the second one has 5 cubs: 2 red and 3 black-brown. What are the genotypes of all parents?
Problem 59.
puppies: 2 shorthaired black and 2 shorthaired coffee. What is the genotype of the dog bought by the hunter
Problem 60. "Smuggler"
In the small state of Lisland, foxes have been bred for several centuries. Fur is exported, and the money from its sale forms the basis of the country's economy. Silver foxes are especially prized. They are considered a national treasure, and transport across the border is strictly prohibited. A cunning smuggler who studied well at school wants to deceive customs. He knows the basics of genetics and suggests that the silver color 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 Lysland?
Related tasks
"Linked Inheritance (Crossing Over)"
Task 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 Morganids.
Problem 62.
In tomatoes, high growth dominates over dwarf, spherical shape of fruits - over pear-shaped. The genes responsible for these traits are linked at a distance of 5.8 Morganids. They crossed a diheterozygous plant and a dwarf plant with pear-shaped fruits. What will be the offspring?
Problem 63.
Problem 64 .
Crossed two lines of mice: in one of them, animals with crimped hair of normal length, and in the other - with long and straight. The hybrids of the first generation were with a straight coat of normal length. In the analyzing crossing of hybrids of the first generation, 11 mice were obtained with normal straight hair, 89 with normal crimped, 12 with long crimped, 88 with long straight. Arrange genes on chromosomes.
* Task 65 for the construction of chromosome maps
Experience has established
that the percentage of crossover between genes is:
| A) A - B \u003d 1.2% B - C \u003d 3.5% A - C \u003d 4.7 | B) C - N = 13% C - P = 3% P - N = 10% C - A = 15% N - A = 2% |
| C) 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 the genes on the chromosome.
Demo tasks USE materials
different years
Part A.
The AABB x aavb scheme illustrates the crossing:
1. monohybrid 2. polyhybrid
3. analyzing dihybrid
4. analyzing monohybrid
Specify the person's genotype if he is fair-haired and blue-eyed (recessive traits)
1. AABB 2. AABB 3. AABB 4. AABB
Homozygous dominant gray sheep die when switching to roughage, while heterozygous ones survive. Determine the genotype of a gray viable individual
1. Aa 2. AA 3. AaBv 4. AaBV
In dogs, black coat color dominates over brown, short legs - over normal leg length. What is the genotype of a brown short-legged dog homozygous for leg length.
1. aaBv 2. aavb 3. AaBb 4.aaBb
In peas, the yellow color of the seeds dominates over the green, the smooth shape of the seeds - over the wrinkled. Determine the genotype of a homozygous plant with yellow wrinkled seeds
1. AABB 2. AABB 3. AABB 4. AABB
What gametes do individuals with the aaBB genotype have?
1. aa 2. aaBB 3. BB 4. aB
In an individual with the Aavv genotype, gametes are formed
1. Av, cc 2. Av, av 3. Aa, AA 4. Aa, cc
What genotype will have offspring in F1 when tomato plants with genotypes AAbb and aaBB are crossed?
1. aaBv 2. AaBb 3. AaBb 4. Abb
What is the probability of having tall children (recessive trait) in heterozygous parents of short stature
1. 0% 2. 25% 3. 50% 4. 75%
When a heterozygous individual is crossed monohybridly with a homozygous recessive one, their offspring are splitting according to the phenotype in the ratio
1. 3: 1 2. 9: 3: 3: 1 3. 1: 1 4. 1: 2: 1
What percentage of pink flowered night beauty plants can be expected from a cross between red and white flowered plants (incomplete dominance)?
1. 25% 2. 50% 3. 75% 4. 100%
What ratio of traits by phenotype is observed in the offspring during analyzing crosses, if the genotype of one of the parents is AaBv (the traits are inherited independently of each other)?
1. 1:1:1:1 2. 1:1 3. 3:1 4. 1:2:1
What phenotype can be expected in the offspring of two white-coated guinea pigs (recessive trait)
1. 100% white
2. 25% white and 75% black
3. 50% white and 50% black
4. 75% white and 25% black
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
Determine the genotypes of the parent pea plants if 50% of plants with yellow and 50% with green seeds were formed during crossing (recessive trait)
1. AA and aa 2. Aa and Aa 3. AA and Aa 4. Aa and aa
When crossing two guinea pigs with black hair (dominant trait), offspring were obtained, among which individuals with white hair accounted for 25%. What are the genotypes of the parents?
1. AA x aa 2. Aa x AA 3. Aa x Aa 4. AA x AA
A girl develops from an egg if chromosomes are found in the zygote during fertilization
1. 44 autosomes + XX
2. 23 autosomes + X
3. 44 autosomes + XY
4. 23 autosomes + Y
Eye color in humans 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 color blind
1. AA XD XD 2. Aa Xd Xd 3. Aa XD Xd 4. aa XD Xd
Albinism is determined by a recessive autosomal gene, and hemophilia by a recessive sex-linked gene. Specify the genotype of the woman - albino, hemophilic.
1. AaXHY or AAXHY 2. AaXHXH or AA XHXH
3. aaXhY 4. aaXhXh
In family healthy parents a boy with hemophilia was born. What are the genotypes of the parents?
1. XH Xh and XhY 2. XH Xh and XHY
3. XH XH and XHY 4. Xh Xh and XHY
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 scheme for solving the problem. Determine the genotypes of the 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 blue color eye (A), and the gene for color blindness is recessive (color blindness - d) and is 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 scheme for solving the problem. Determine the genotypes of the parents and possible offspring, the probability of having color-blind children with brown eyes in this family, and their gender.
6. According to the pedigree shown in the figure, establish the nature of the inheritance of the trait highlighted in black (dominant or recessive, sex-linked or not), the genotypes of children in the first and second generation. contrasting signs (For example: brown eyes - blue eyes,
among them there are opposite signs:
high growth - low growth).
Alleles (allelic genes) - genes that determine the development of alternative traits.
Autosomes - chromosomes in which males and females do not differ.
Interaction of genes - the interconnected action of one, two or more pairs of genes that determine the development of the same trait.
Genetics - the science of heredity and variation.
Genotype - the sum of genes an organism receives from its parents.
heterozygote ("hetero"="different") - an organism with different alleles in the genotype (for example: Aa)
Hybrid generation - generation from parents with different traits.
hybrid - one organism from the hybrid generation.
Homozygote ("homo" = "same") - an organism with the same alleles in the genotype (for example: AA or aa)
Dominant trait - dominant feature (feature that suppresses the rest): A, B, C, ...
Domination - the simplest form of gene interaction according to the "dominance - recessive" type, established by G. Mendel.
Variability - the common property of all organisms to acquire new characters (within a species).
Codominance - a form of gene interaction in which both alleles are manifested in heterozygotes (for example, inheritance of 4 blood groups in humans: AB).
Complementarity - a form of gene interaction when one gene complements the action of another gene.
Locus - the location of the gene on the chromosome.
Mendel Gregor (Czech monk) - the founder of genetics.
Morgan Thomas (American scientist) - creator of the chromosome theory of heredity.
Heredity - the common property of all organisms to transmit their traits to their descendants.
incomplete dominance - the case when the heterozygous offspring has an intermediate phenotype.
Sex chromosomes - chromosomes in which males and females differ.
Polymeria - a form of gene interaction in which one trait is determined by several equivalent pairs of genes.
recessive trait - repressed trait (a trait that is suppressed by the dominant): a, b, c, ...
Phenotype - the sum of the external and internal features of the body.
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 tasks in genetics / Biology magazine for schoolchildren No. 4 - 2005.
Bashurova T.I. Fairy tale tasks in genetics / Biology magazine: September 1, No. 8 - 2012.
Gulyaev G.V. Task book on genetics, - M., Kolos, 1980.
Zhdanov N. V. Problem solving in the study of the topic “Population genetics”. - Kirov, ped. inst., 1995.
Tasks in genetics for applicants to universities. -
Volgograd, Teacher, 1995.
Kochergin B. N., Kochergina N. A. Tasks for molecular biology and genetics, - Minsk, People's Asveta, 1982.
Brief collection of genetic problems, - Izhevsk, 1993.
Methodical development for students biological department VZMSh at Moscow State University Mendel's Laws, - M., 1981.
Guidelines for self-study to practical training in general genetics. - Perm, honey. inst. 1986.
Murtazin G. M. Tasks and exercises for general biology. - M., 1981.
Orlova N. N. “Small workshop on general genetics / collection of tasks. - Ed. Moscow State University, 1985.
Collection of problems in biology / teaching aid for applicants to medical. inst. - Kirov, 1998.
Sokolovskaya B.Kh. One hundred problems in molecular biology and genetics. - M., 1981.
Fridman M.V. Tasks in genetics for school olympiad Moscow State University / magazine Biology for schoolchildren No. 2 - 2003.
Shcheglov N. I. Collection of tasks and exercises in genetics. - MP Ecoinvest, 1991.
http://www.ege.edu.ru/
Sources of illustrations:
domination manifests itself in cases where one allele of a gene completely hides the presence of another allele. However, more often than not, the presence of a recessive allele is somehow affected and usually one has to meet with varying degrees of incomplete dominance.
Complete dominance . On the example of G. Mendel's experiments with peas, it can be seen that one gene can completely suppress the manifestation of another allelic gene. incomplete dominance. With incomplete dominance, the trait in the first generation also manifests itself intermediately between the parental forms. If long-eared Karakul sheep are mated with earless ones, then in F1 all offspring will be short-eared. Cleavage in F2 by phenotype and genotype is the same (1:2:1).
Codominance . In the phenotype, both allelic genes are manifested, showing neither dominance nor recessiveness among themselves. In humans, ABO blood systems are known, which determine erythrocyte antigens. Alleles A and B interact by 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 that define 369 phenogroups, which can be about two trillion different combinations - serological types. Phenogroup- a group of antigens (sometimes one antigen), which are the phenotypic expression of the totality of individual genes of one locus. Blood groups, which are based on the individual characteristics of the antigenic properties of erythrocytes, are hereditarily determined 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 vast majority of known allelic erythocyte factors are inherited by the type of codominance.
Overdominance e. It is characterized by the fact that in heterozygous individuals the trait is stronger than in homozygous dominant ones, that is, the hybrid surpasses both parents in the development of the trait. Such a phenomenon is called heterososomes(Aa>AA and a a). A good example of overdominance is human sickle-shaped anemia. Homozygotes of SS have part of the erythrocytes in the form of a sickle and arrowhead, they have impaired oxygen transport by erythrocytes. People suffer from an acute form of anemia and usually die at an early age. Heterozygotes Ss are resistant to tropical malaria, homozygotes ss get sick with 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 established that affect the color of the hairline: C - black, cch - chinchilla, ch - Himalayan, ca - albino Alleles are presented in descending order of dominance (C>cch>ch>ca).The C allele dominates all subsequent ones, ca is recessive to all previous ones.
Pleiotropic action of the gene . A gene can influence the development of two or more traits, that is, there is a multiple effect of the gene. This type of interaction was found when breeding Karakul sheep of gray color (Shirazi) and black (Arabi). Lambs homozygous for the dominant allele of the C gene, which determines the gray color (Shirazi). when switching to pasture, they die due to the 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 a gray color 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 viability of the body up to death. One of the reasons for changing the splitting ratio is 3:1. is the different viability of homozygotes in F2. In the XX century. facts were discovered when a 2:1 splitting occurred in the phenotype. So, when studying the inheritance of color in yellow and black mice, splitting in color into 2 parts of yellow and 1 part of black mice was observed. At the same time, part of the yellow mice died in the embryonic period. The same gene in the dominant heterozygous state caused the yellow coloration of mice, and in the homozygous state it showed its lethal effect. The black 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 crossing platinum foxes between themselves, the individuals had both platinum and silver-black color in a ratio of 2:1. When carrying out analyzing crosses, it became clear that the platinum color gene is dominant. It has been suggested that homozygous platinum foxes (AA) die in the embryonic period. Autopsy of pregnant females confirmed this assumption. Recessive lethal genes act in homozygous state, and dominant - and in heterozygous. If the gene does not cause the death of the organism, but significantly reduces the 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 coat in newborn calves, rabbits and animals of other species. Shortly after birth, these animals die.
Semi-legal genes can cause deformities in animals: shortening of the axial skeleton; deformation of the head, limbs; violation of the physiological functions of the body. Breeding animals with lethal and semi-lethal genes must be culled. Particularly carefully it is necessary to check breeding producers, from which a large number of offspring are obtained during artificial insemination.
There are two types of alleles (gene variants)- dominant and recessive.
Dominant a gene is called, the functional activity of which does not depend on the presence in the body of another gene of this trait. The dominant gene is thus dominant, it appears already in the first generation.
recessive called a gene that provides the development of a trait only in the absence of other variants of this gene in the body. The recessive gene may appear in the second and subsequent generations. For the manifestation of a trait formed by a recessive gene, it is necessary that the offspring receive the same recessive variant of this gene from both the father and the mother (ie, in the case of homozygosity). Then, in the corresponding pair of chromosomes, both sister chromosomes will have only this one variant, which will not be suppressed by the dominant gene and can manifest itself in the phenotype.
4.2.Homo- and heterozygous organisms.
Gregor Mendel was the first to establish a fact indicating that plants similar in appearance, can differ sharply in hereditary properties.
Individuals that do not split in the next generation are called homozygous.
Individuals in whose offspring a splitting of traits is found are called heterozygous.
Homozygosity- This is a state of the hereditary apparatus of the body, in which homologous chromosomes have the same form of a given gene. The transition of a gene to a homozygous state leads to the manifestation in the structure and function of the organism (phenotype) of recessive alleles, the effect of which, when heterozygous, is suppressed by dominant alleles.
The test for homozygosity is the absence of segregation in certain types of crossing. A homozygous organism produces only one type of gamete for this gene.
The homozygosity of an allele is called the presence in it of two identical genes (carriers hereditary information): either two dominant or two recessive.
Heterozygosity- this is a state inherent in any hybrid organism, in which its homologous chromosomes carry different forms(alleles) of a particular gene or differ in the relative position of the genes. Heterozygosity occurs when gametes of different quality in terms of genetic or structural composition merge into a heterozygote.
Heterozygosity is detected by analyzing crosses. Heterozygosity, as a rule, is a consequence of the sexual process, but may result from a mutation.
Allele heterozygosity is called the presence in it of two different genes, i.e. one is dominant and the other is recessive.
4.3.Dominance types.
In addition to complete dominance, when the dominant gene overlaps the action of the recessive gene, there are known its other types:
intermediate inheritance,
incomplete dominance,
overdominance,
Codominance.
With intermediate inheritance offspring in the 1st generation retains uniformity, but has an intermediate character. For example, when crossing a red-flowered night beauty with a white-flowered one, individuals with pink flowers were obtained in the 1st generation.
Sometimes the trait tends to lean more towards the parent with the dominant trait, this is called incomplete dominance. For example, when crossing piebald cows (white spots on the body, white belly, white legs) with bulls that have a solid color, offspring are obtained that have separate white spots - i.e. solid coloration incompletely dominates piebald.
Overdominance of hybrids manifested by heterosis - the phenomenon of the superiority of offspring over parental forms in terms of viability, fertility and productivity (such, for example, is a mule - a hybrid of a donkey and a horse).
Codominance- in a hybrid individual, both parental traits are equally manifested, this is how blood groups are inherited.
4.4.Types of inheritance.
1. Autosomal dominant type of inheritance:
a. With a sufficient number of descendants, the trait is found in each generation
b. A rare trait is inherited by about half of children
in. Male and female offspring inherit this trait equally.
d. Both parents equally pass on this trait to their children.
2. Autosomal recessive type of inheritance:
a. A trait can be passed down through generations even with a sufficient number of offspring
b. The symptom can manifest itself in children in the absence of it in the parents. Found then in 25% of cases in children
in. The trait is inherited by all children if both parents are sick
d. A sign in 50% develops in children if one of the parents is sick
e. Male and female offspring inherit this trait equally.
3. Inheritance linked to the X chromosome, if the gene that controls the manifestation of the trait is recessive:
a. Men inherit more often than women
b. Girls inherit this trait only from their father.
in. In marriages where both spouses are healthy, children can be born with it, while it is inherited by 50% of sons and 100% of healthy daughters
d. There is an alternation of sick men in generations: where there are more of them, where - less
4. Inheritance linked to the X chromosome, if the gene that controls the manifestation of the trait is dominant:
a. Men inherit less than women
b. If the trait is only in the spouse, then all children inherit it (homozygous mother), or half of the children (heterozygous mother)
in. If only from the spouse, then all females inherit
5. Inheritance linked to the Y chromosome:
a. Only sons suffer, in each generation it manifests itself if the father is sick.
