Blue eyes are the result of a genetic mutation. In humans, the gene for brown eyes dominates over the gene that determines the development of blue eyes, and the gene that determines the ability to better use the right hand. Basic situations of gene interaction
ANSWER: The offspring always receives only one gene from the alleles from their parents. Since a blue-eyed girl was born, it means that she received one blue-eyed gene from her mother, i.e. she was heterozygous for this trait and her genotype was Aa. The genotype of the blue-eyed father is aa (a recessive trait appears only in the homozygous state)
GAMES (G) A, a a
ANSWER: Aa and aa; probability of having brown-eyed children is 50%
- In humans, non-red hair is dominant over red hair. Father and mother are heterozygous brown. They have eight children. How many of them might be redheads? Is there a clear answer to the question?
ANSWER: Since the parents are heterozygous, they carry one gene for red hair. Theoretically, they can have 2 red-haired children (25%). But the meeting of gametes during fertilization occurs by chance and therefore in a given family all non-red or all red-haired people can be born.
- The black color of the fur of minks dominates over the blue. How to prove the purebred nature of two black minks purchased by a fur farm?
ANSWER: Both heterozygous and homozygous individuals can have black coloration. But purebred individuals are homozygous and do not produce segregation in the offspring. To find out the genotypes of purchased minks, you need to cross them with blue minks. If blue minks appeared in the offspring, it means that the mink was not purebred, that is, heterozygous (Aa); if there is no cleavage - homozygous (AA).
- A brown-eyed right-hander married a blue-eyed left-hander. They gave birth to a blue-eyed left-hander. Determine the mother's genotype (brown eyes and right-handedness are dominant).
ANSWER: Since their child exhibited recessive genes for both traits, he received one of them from each parent, i.e. the mother was heterozygous for two traits and her genotype was AaBb.
- Black coat color (A) dominates over white coat (a), and shaggy coat (B) dominates over smooth coat (c). What phenotypic cleavage should be expected from crossing two rabbits heterozygous for two traits?
ANSWER: Since the parents are diheterozygous, they have the AaBb genotype, and with such a crossing, a phenotypic split is manifested in the offspring - 9: 3: 3: 1.
- What is the probability of having a blue-eyed (a), fair-haired (c) child from the marriage of a blue-eyed, dark-haired father with the aaBb genotype and a brown-eyed, fair-haired mother with the Aabv genotype?
ANSWER: R Aavv X aaVv
GAMETES (G) Av, av aB, av
AaVv Aavv aaVv aavv
K.t. k.s g.t. g.s.
ANSWER: 25%.
- When crossing two varieties of tomato with red spherical and yellow pear-shaped fruits in the first generation, all the fruits are spherical and red. Determine the genotypes of parents, first-generation hybrids, and the ratio of second-generation phenotypes.
ANSWER:
1) genotypes of the parents: red spherical fruits - AABB,
yellow pear-shaped fruits – aabb
2) genotypes F 1: red spherical AaBb
3) ratio of phenotypes F 2:
9 – red spherical
3 – red pear-shaped
3 – yellow spherical
1 – yellow pear-shaped
- A blue-eyed man, both of whose parents are brown-eyed, married a brown-eyed woman whose mother is blue-eyed and whose father is brown-eyed. From the marriage a blue-eyed son was born. Make a pedigree and indicate the genotypes of all relatives.
ANSWER: 1) First, we draw up a pedigree diagram and sign the phenotypes.
2) Then, we write down the genotypes of individuals who have a recessive trait, i.e. homozygous for this gene.
3) These individuals transmit (parents) or receive (children) one recessive gene, so we write these genes in the genotype of children or parents.
4) In persons with a dominant trait, we write down the genotype first one dominant gene And according to the scheme, their homozygosity or heterozygosity will be revealed
. 
- What blood types are possible in children if the mother has the first blood group and the father has the fourth?
SOLUTION: The first group is determined by the OO genotype, the fourth - AB. Alleles A and B are dominant to allele O.
2nd group 3rd group
ANSWER: Children will have 2 and 3 blood groups.
- The genes for coat color in cats are located on the X chromosome. Black coloring is determined by the gene X B red - X b, heterozygotes have a tortoiseshell color. One tortoiseshell and one black kitten were born from a black cat and a ginger cat. Determine the genotypes of parents and offspring, the possible sex of kittens. Solution:
P X B X B x X b Y
F 1 X B Y X B X b
ANSWER: genotype of a black cat X B X B, genotype of a red cat - X b Y, genotypes of kittens: tortoiseshell - X B X b
Black - X V U, gender of kittens: tortoiseshell - female, black - male.
- Two black female mice were crossed with a brown male. The first female gave birth to 20 black and 17 brown offspring in several litters, and the second female gave birth to 33 black offspring. Determine the genotypes of parents and offspring, explain the answer.
ANSWER: Since there was no splitting in the offspring of the second black female, all the offspring were black, which means that black color is dominant and the genotype of the male is aa, the genotype of the second female is AA. In the offspring of the first female, a 1:1 split is observed, which means that the genotype of the first female is Aa. The genotypes of the offspring from the first female are Aa (20 black) and aa (17 brown), the genotype of the offspring from the second female is Aa (uniformity - 33 black).
- In a family where the parents have normal color vision, the son is color blind. The genes for normal color vision (D) and color blindness (d) are located on the X chromosomes. Determine the genotypes of the parents, the colorblind son and the likelihood of having children who are carriers of the colorblind gene.
ANSWER: Genotypes of parents: mother – X D X d, father X D Y; the genotype of the son is colorblind -X d Y; the probability of being born as carriers of the color blindness gene (X D X d) is 25%.
- Prove that the genotype is an integral system.
ANSWER: The genotype is an integral system, because there are interactions between allelic and non-allelic genes (dominance, codominance, complementarity, etc.), one gene can influence the development of several traits, several genes can influence the development of one trait.
- Healthy parents have a son with hemophilia. Determine the genotypes of the parents, their son, the likelihood of having sick children and carriers of the hemophilia gene in these parents, if the hemophilia gene (h) is recessive and sex-linked.
ANSWER: genotypes of the parents: mother - X N X h, father - X H Y; son's genotype - X h Y; the probability of having sick children is 25% (sons), 25% of sons are healthy, daughters are healthy (Х Н Х H, Х Н Х h), but half of the daughters are carriers of the hemophilia gene
- What is the essence of T. Morgan's chromosome theory of heredity?
ANSWER: Genes are located linearly on a chromosome. Genes on the same chromosome form a linkage group and are therefore inherited together. The number of linkage groups is equal to the haploid set of chromosomes. Disruption of gene linkage occurs in the process of crossing over, the frequency of which depends on the distance between genes - the greater the distance between genes, the greater the frequency of crossing over.
- A man with normal vision married a colorblind woman (the recessive gene d is linked to the X chromosome). Determine the genotypes of the parents, the ratio of phenotypes and genotypes in the offspring.
ANSWER: Genotypes of parents: mother – X d X d, father X D Y; genotypes of the offspring: all daughters are carriers of the color blindness gene - X D X d, all sons are color blind - X d Y; the ratio of sick and healthy children is 1:1 or 50%:50%.
- Crossed two snapdragon plants with red and white flowers. Their offspring turned out to have pink flowers. Determine the genotypes of parents, first-generation hybrids and the type of inheritance of the trait.
ANSWER: The appearance of an intermediate trait in the offspring indicates incomplete dominance of the trait. Genotypes of parental plants (P): AA and aa. Gametes: A And A. First generation genotypes: Aa.
- Using the pedigree presented in the figure, establish the nature of inheritance of the trait highlighted in black (dominant or recessive, sex-linked or unlinked), and the genotypes of children in the first and second generations.
ANSWER: 1) The trait is dominant, since it is always transmitted to offspring, and is not sex-linked, since it is transmitted equally to both daughters and sons. 2) genotypes of children in F 1 women - ahh And Ahh
Men - aa and aa. Genotypes of descendants F 2 man - Ah. Genotypes of parents: female : ahh , man Ah.
- When crossing a tomato with a purple stem (A) and red fruits (B) and a tomato with a green stem and red fruit, 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.
ANSWER: parental genotypes: purple stem, red fruits - AABb (gametes: AB and Ab); green stem, red fruits –aaBb (gametes aB and ab); genotypes of offspring in F 1: AaBB, AaBb, Aabb; ratio of genotypes and phenotypes in F 1:
purple stem, red fruits – 1 AaBB: 2 AaBb
purple stem, yellow fruit – 1 Aabb.
- Using the pedigree shown in the figure, determine the nature of the manifestation of the trait (dominant, recessive), indicated in black. Determine the genotype of parents and children in the first generation.
ANSWER: 1) the trait is recessive;
2) genotypes of the parents: mother - aa, father - AA or Aa;
3) genotypes of children: heterozygous son and daughter - Aa (allowed: other genetic symbolism that does not distort the meaning of solving the problem, indicating only one of the options for the father's genotype).
- 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?
ANSWER: Genotypes and phenotypes P: aa – with small molars, Aa – without small molars; genotypes and phenotypes of the offspring: Aa – without small molars, aa – with small molars; the probability of having children without small molars is 50%.
- What underlies the combinative variability of organisms? Explain your answer.
ANSWER: The basis of combinative variability is the following processes:
- crossing over leads to a change in the combination of genes in homologous chromosomes;
- meiosis, which results in independent segregation of chromosomes into gametes;
- random combination of gametes during fertilization.
- 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), and the genotypes of children in the first and second generations.
ANSWER:
- the trait is dominant, not sex-linked;
- genotypes of children of the 1st generation: daughter Aa, daughter aa, son Aa;
- genotypes of children of the 2nd generation: daughter Aa
| 1 2 | Symbols man woman marriage Children of the same marriage - manifestation of the trait under study |
- Based on the person’s pedigree presented in the figure, establish the nature of inheritance of the “small eyes” trait, highlighted in black (dominant or recessive, sex-linked or not). Determine the genotypes of the parents and offspring F(1, 2, 3, 4, 5).
ANSWER: 1) the trait is recessive, not sex-linked (since it is transmitted to both daughters and sons); 2) genotypes of parents: Aa x Aa; 3) genotypes of descendants in F1: 1,2- Aa; 3 – AA or Aa; 4, 5 - aa.
Standards of answers to tasks Line C1 Excellent exam 2010
1. What is the role of nucleic acids in protein biosynthesis? Answer:
Answer elements: information is copied from DNA to RNA, which transfers it from the nucleus to the ribosome, mRNA. serves as a matrix for the assembly of protein molecules; tRNAs attach amino acids and deliver them to the assembly site of the protein molecule to the ribosome.
2. Ribosomes from different cells, the entire set of amino acids and identical molecules of mRNA and tRNA were placed in a test tube, and all conditions for protein synthesis were created. Why will one type of protein be synthesized on different ribosomes in a test tube?
Answer: The primary structure of a protein is determined by the sequence of amino acids; The templates for protein synthesis are identical mRNA molecules, in which the same primary protein structure is encoded.
3. The process of photosynthesis occurs intensively in the leaves of plants. Does it occur in ripe and unripe fruits? Explain your answer.
Answer elements: 1) photosynthesis occurs in unripe fruits (while they are green), since they contain chloroplasts; 2) as the chloroplast matures, they transform into chromoplasts, in which photosynthesis does not occur.
4. Why does it need to be lubricated with an oily liquid to remove a tick that has attached itself to a person’s body? Answer:
1) the oily liquid closes the openings of the trachea, which are the respiratory organs of ticks
2) flares die from lack of oxygen and are easily removed.
5. Explain what toothless and pearl barley feed on and why they are called “bottom filters”. Answer:
Toothless and pearl barley feed on organic particles, which with a current of water enter the mantle cavity and are filtered by cilia, passing a large amount of water through themselves, they cleanse it of organic and impurities and microorganisms.
6. Why is it recommended to drink salted water in the summer when you are thirsty for a long time?
Answer elements: in summer a person sweats more; mineral salts are removed from the body through sweat; salted water restores the normal water-salt balance between tissues and the internal environment of the body.
7. Why are passengers recommended to suck lollipops when taking off or landing an airplane? Answer:
Answer elements: 1) rapid changes in pressure during takeoff or landing of an airplane cause discomfort in the middle ear, where the initial pressure on the eardrum persists longer; 2) swallowing movements improve air access to the auditory (Eustachian) tube, through which the pressure in the middle ear cavity is equalized with the pressure in the environment.
8 What plant organs are damaged by cockchafers at different stages of individual development? Answer:
1) plant roots are damaged by larvae; 2) tree leaves are damaged by adult beetles.
9. The introduction of large doses of drugs into the patient’s vein is accompanied by their dilution with saline solution (0.9% NaCl solution). Explain why.
Answer: 1) the concentration of saline solution (0.9% NaCl solution) corresponds to the concentration of salts in the blood plasma and does not cause the death of blood cells; 2) administration of large doses of drugs without dilution can cause a sharp change in blood composition and irreversible phenomena
10. What processes maintain the constancy of the chemical composition of human blood plasma? Answer:
Answer elements: 1) processes in buffer systems maintain the reaction of the environment (pH) at a constant level; 2) neurohumoral regulation of the chemical composition of plasma is carried out.
11. What is the reason for the need for iron ions to enter the human blood? Explain your answer. Answer:
Answer elements: 1) iron ions are part of the hemoglobin of erythrocytes; 2) red blood cells provide transport of oxygen and carbon dioxide.
12. In ancient India, a person suspected of a crime was offered to swallow a handful of dry rice. If he failed, guilt was considered proven. Give a physiological basis for this process. ,
Answer: 1) swallowing is a complex reflex act, which is accompanied by salivation and irritation of the tongue; 2) with strong excitement, salivation is sharply inhibited, the mouth becomes dry and the swallowing reflex does not occur.
13. What processes ensure the movement of water and minerals throughout the plant? Explain your answer. Answer:
1) from the root to the leaves, water and minerals move through the vessels due to transpiration, as a result
by which the sucking force arises; 2) the upward current in racegenia is facilitated by root pressure, which arises as a result of the constant flow of water into the root due to the difference in the concentration of substances in the cells and the environment.
14. Why are owls in a forest ecosystem classified as second-order consumers, and mice as first-order consumers? Answer:
Answer elements: 1) owls feed on herbivores, therefore they are classified as second-order consumers; 2) mice eat plant foods, so they are classified as first-order consumers.
15. Why is the relationship between pike and perch in a river ecosystem considered competitive?
Answer elements: 1) are predators, feed on similar food; 2) live in the same body of water and need similar
living conditions mutually oppress each other
16. Why can the number of commercial herbivorous fish sharply decrease when predatory fish are destroyed in a reservoir?
Elements of the answer: 1) the destruction of predators leads to a sharp increase in the number of herbivorous fish and increased competition between them; 2) a large number of herbivorous fish contributes to a decrease in the food supply, the spread of various diseases among them, this will lead to mass death of fish.
17. What serves as the basis for the formation of diverse food networks in ecosystems? Answer:
1) diversity of species, the presence of producers, consumers, and decomposers among them; 2) feeding species with a variety of foods (broad food specialization).
18. Explain why beef that has not passed sanitary control is dangerous to eat undercooked or lightly cooked.
Answer elements: 1) beef meat may contain bovine tapeworm; 2) an adult worm develops from the finna in the digestive canal, and the person becomes the final host.
19. Explain why growing legumes does not require fertilizing with nitrogen fertilizers. Answer:
Answer elements: I) nodule bacteria settle on the roots of legumes; 2) they absorb nitrogen from the air and provide plants with nitrogen nutrition.
20. What is the protective role of leukocytes in the human body? Answer:
Elements of the answer: 1) leukocytes are capable of phagocytosis - devouring and digesting proteins, microorganisms, dead cells; 2) leukocytes take part in the production of antibodies that neutralize certain antigens.
21. Which milk, sterilized or freshly milked, will sour faster under the same conditions? Explain your answer. Answer:
Answer elements: 1) freshly milked milk will sour faster, since it contains bacteria that cause fermentation of the product; 2) when milk is sterilized, the cells and spores of lactic acid bacteria die and the milk lasts longer.
22. Why is the volume of urine excreted by the human body per day not equal to the volume of liquid drunk during the same time? Answer:
Answer elements: 1) part of the water is used by the body or formed in metabolic processes; 2) part of the water evaporates through the respiratory organs and through the sweat glands.
23. Why can treating a person with antibiotics lead to intestinal dysfunction? Give at least two reasons.
Answer: 1) antibiotics kill beneficial bacteria that live in the human intestines; 2) the breakdown of fiber, water absorption and other processes are disrupted.
24. Red algae (purple algae) live at great depths. Despite this, photosynthesis occurs in their cells. Explain how photosynthesis occurs if the water column absorbs rays from the red-orange part of the spectrum.
Answer elements: 1) photosynthesis requires rays of the red and blue parts of the spectrum; 2) the cells of scarlet mushrooms contain a red pigment that absorbs rays from the blue part of the spectrum, their energy is used in the process of photosynthesis.
25. The color of the white hare’s fur changes throughout the year: in winter the hare is white, and in summer it is gray. Explain what type of variability is observed in the animal and what determines the manifestation of this trait.
Answer elements: 1) the hare exhibits modification (phenotypic, non-hereditary) variability;
2) the manifestation of this trait is determined by changes in environmental conditions (temperature, day length).
26. Which of the following types of fuel - natural gas, coal, nuclear energy - contribute to the creation of the greenhouse effect? Explain your answer.
Answer elements: 1) natural gas and coal contribute to the creation of the greenhouse effect; 2) when they are burned, carbon dioxide is formed, which creates a greenhouse effect.
27. Frozen apples release a sweetish juice when thawed. What is this connected with?
1). When water freezes, it expands, thereby compromising the integrity of tissues, cells, and organelles; 2) after thawing, cell sap containing sugary substances flows out of the cell vacuoles.
28. Why is the soil in forest plantations populated with mycorrhizal fungi?
1). Trees enter into symbiosis with fungi; 2) plant roots receive additional mineral nutrition, plants tolerate unfavorable conditions more easily.
29. What is the purpose of picking plants?
1). When picking, the tip of the main root is removed, which promotes the development of lateral roots; 2) as a result, the plant nutrition area increases.
30. What is the role of chemosynthetic bacteria in ecosystems?
1). Form organic substances from inorganic ones; 2). They are classified as producers and in ecosystems they form the first link in the food chain.
31. What processes ensure the movement of water and minerals throughout the plant? Explain your answer.
Elements of the answer: 1) from the root to the leaves, water and minerals move through the vessels due to transpiration, as a result of which suction force arises; 2). the upward flow in the plant is facilitated by root pressure, which arises as a result of the constant flow of water into the root due to the difference in the concentration of substances in the cells and the environment.
32. The process of photosynthesis occurs intensively in the leaves of plants. Does it occur in ripe and unripe fruits? Explain your answer.
Answer elements: 1) photosynthesis occurs in unripe fruits (while they are green), since they contain chloroplasts; 2) as they mature, chloroplasts turn into chromoplasts, in which photosynthesis does not occur.
33. The circulatory system of insects is not associated with the transport of gases. How are they transported throughout the body of animals?
1). Gases are transported through the respiratory system; 2). The respiratory system is represented by a network of branched tracheas, through which oxygen is delivered directly to the cells, and carbon dioxide enters the tracheas from the cells.
34. What is a conditioned reflex and what is its role in the life of an animal?
1), reflexes acquired by humans and animals throughout life, formed on the basis of unconditioned 2). Helps the body adapt to specific living conditions.
35. You can sometimes see a large number of earthworms on the soil surface. Explain under what meteorological conditions this occurs and why?
1). Observed after heavy rain, earthworm tunnels fill with water; 2). The oxygen content decreases, the breathing of worms in the soil becomes difficult and they migrate to the surface.
Many mothers, while expecting a baby, often think about how he will be born, what color eyes and hair he will have, what nose, lips and height he will have. Will he look like his parents or will he inherit the features of one of his relatives? Genetics can provide answers to these questions even before the baby is born.
Based on the laws of genetics, let's look at the algorithms by which a child's appearance is most often formed.
Eye color
If dad has dark brown eyes and mom has blue eyes, then the child is likely to have brown eyes. The gene for brown eyes is dominant (strong), and the gene for blue eyes is recessive (weak). If both parents have brown eyes, then they are unlikely to have a child with green, gray or blue eyes. As time passes, they will begin to darken, gradually turning brown.
But if both parents are blue-eyed, then the baby will most likely have blue eyes.
Dominant traits
If at least one parent has dimples on the cheeks, a hooked (or large/crooked) nose, or protruding ears, then there is a very high probability that the child will also have this appearance feature. The fact is that these, as we generally believe, shortcomings are dominant signs and “peck out” in the baby’s appearance.
But, as a rule, only one such feature appears, less often - two at once.
Hair color
The gene for dark hair outweighs the gene for light hair because its pigment is strong. If both parents are fair, then the baby will also be born blonde or light brown. And if dad is a bright brunette, and mom is blonde, then the baby’s hair will be dark or light brown.
Interesting fact: a child who was born dark from this combination may have light-colored children in the future. The fact is that children of mixed genes receive both a strong gene from their father and a weak gene from their mother. Later, the weak gene can “merge” with the weak gene of the partner - and the child’s appearance will be light.
Also, the child may be completely different from you if he inherits wandering genes from distant relatives. Thus, in a brown-haired family, a red-haired baby may suddenly be born, and there are also cases when a dark-skinned child was born to white-skinned parents, even if there were mulattoes in the family even several generations ago.
Source: instagram @sarahdriscollphoto
Curly or smooth hair
Wavy and curly hair is also a dominant trait that is most likely to appear in a child if at least one of the parents has it.
3) One of the forms of glaucoma is determined by a dominant autosomal gene, and the second has an autosomal recessive type of inheritance. These genes are located on different pairs of chromosomes.
What is the probability of having a sick child if both parents are diheterozygous?
4) The gene for black color in cats is sex-linked. The other allele of this gene corresponds to the red color; heterozygous animals have a spotted ("tortoiseshell") coloration.
What will be the offspring from crossing a “tortoiseshell” cat with a ginger cat?
5) The forensic medical examination is tasked with finding out whether the boy in the family is his own or adopted. A blood test of the husband, wife and child showed: the wife is Rh-AB-IV blood type, the husband is Rh+O (I) blood type, the child is Rh-B (III) blood type.
What conclusion should the expert give and on what is it based?
6) When crossing a brown Great Dane with a white one, all the offspring are white. When breeding the resulting offspring "in themselves" we got 40 white, 11 black and 3 brown.
What type of gene interaction determines the inheritance of coat color in Great Danes? What is the genotype of the parents and offspring?
7) In chickens, striped color is due to the sex-linked dominant (B), and the absence of such striping is due to its recessive alleles (c). The presence of a crest on the head is a dominant autosomal gene (C), and its absence is a recessive allele (c). Two striped, combed birds were crossed and produced two chicks: a striped cockerel with a comb and a non-striped hen without a comb. Indicate the genotypes of the parental forms and offspring.
heard; but one has smooth hair and the other has curly hair, a deaf child was born with smooth hair. Their second child heard well and had curly hair.
What is the probability of having a deaf child with curly hair in such a family?
2) The gene for brown eyes is dominant over the gene for blue eyes. A brown-eyed man whose parent had blue eyes married a brown-eyed woman whose father had blue eyes and whose mother had brown eyes.
What kind of offspring can be expected from this marriage?
Right-handedness predominates over the left-handedness gene. What is the probability of having blue-eyed, left-handed children from the marriage of two diheterozygous parents?
in humans, the gene for brown eyes dominates the gene causing blue eyes, a blue-eyed man, one of whose parents has brown eyes, marriesa brown-eyed woman whose father has brown eyes and whose mother has blue eyes. What kind of offspring can be expected from this marriage.
1. A blue-eyed man, whose parents had brown eyes, married a brown-eyed woman, whose father had blue eyes and whose mother had blue eyes.brown. What kind of offspring can be expected from this marriage if it is known that the gene for brown eyes dominates the gene for blue eyes?
2. There were two brothers in the family. One of them, a patient with hemorrhagic diathesis, married a woman also suffering from this disease. All three of their children (2 girls and 1 boy) were also sick. The second brother was healthy and married a healthy woman. Of their four children, only one was sick with hemorrhagic diathesis. Determine which gene determines hemorrhagic diathesis.
3. In a family where both parents had normal hearing, a deaf child was born. Which trait is dominant? What are the genotypes of all members of this family?
4. A man suffering from albinism marries a healthy woman whose father suffered from albinism. What kind of children can be expected from this marriage, given that albinism is inherited in humans as an autosomal recessive trait?
My friends know how much I am interested in the question of the color of my son's eyes.
For those who don’t know, I’ll tell you: Our dad has brown eyes. My eyes are green with pronounced heterochromia (there are brown veins in the eyes, the rim of the eyes is gray, the iris is green. That is, the eyes are three-colored).
Eye color: from grandparents to our grandchildren: how it is transmitted genetically.
Tables for calculating the eye color of an unborn child.
During pregnancy, many parents are eager to find out what eye color their unborn child will have. All answers and tables for calculating eye color are in this article.
Good news for those who want to pass on their exact eye color to their descendants: it is possible.
Recent research in the field of genetics has discovered new data on the genes that are responsible for eye color (previously 2 genes were known that were responsible for eye color, now there are 6). At the same time, today genetics does not have answers to all questions regarding eye color. However, there is a general theory that, even with the latest research, provides a genetic basis for eye color. Let's consider it.
So: every person has at least 2 genes that determine eye color: the HERC2 gene, which is located on human chromosome 15, and the gey gene (also called EYCL 1), which is located on chromosome 19.
Let's look at HERC2 first: humans have two copies of this gene, one from their mother and one from their father. HERC2 can be brown and blue, that is, one person has either 2 brown HERC2 or 2 blue HERC2 or one brown HERC2 and one blue HERC2:
HERC2 gene: 2 copies* Human eye color
Brown and Brown brown
Brown and blue brown
Blue and cyan blue or green
(*In all tables in this article, the dominant gene is written with a capital letter, and the recessive gene is written with a small letter, eye color is written with a small letter).
Where does the owner of two blue HERC2 green eyes come from - is explained below. In the meantime, here is some data from the general theory of genetics: brown HERC2 is dominant, and blue is recessive, so a carrier of one brown and one blue HERC2 will have brown eye color. However, a carrier of one brown and one blue HERC2 can pass on both brown and blue HERC2 to their children with a 50x50 probability, that is, brown dominance does not in any way affect the transmission of a copy of HERC2 to children.
For example, a wife has brown eyes, even if they are “hopelessly” brown: that is, she has 2 copies of brown HERC2: all children born with such a woman will be brown-eyed, even if the man has blue or green eyes, so how she will pass on one of her two brown genes to her children. But grandchildren can have eyes of any color:
So, for example:
HERC2 from the mother is brown (in the mother, for example, both HERC2 are brown)
HERC2 from father - blue (father, for example, has both HERC2 blue)
The child's HERC2 is one brown and one blue. The eye color of such a child is always brown; at the same time, he can pass on his blue HERC2 to his children (who can also receive blue HERC2 from the second parent and then have eyes either blue or green).
Now let's move on to the gey gene: it can be green and blue (blue, gray), each person also has two copies: a person receives one copy from his mother, the second from his father. Green gey is a dominant gene, blue gey is recessive. A person thus has either 2 blue gey genes or 2 green gey genes, or one blue and one green gey gene. At the same time, this affects the color of his eyes only if he has blue HERC2 from both parents (if he received brown HERC2 from at least one of his parents, his eyes will always be brown).
So, if a person received blue HERC2 from both parents, depending on the gey gene, his eyes may be the following colors:
Gey gene: 2 copies
Human eye color
Green and Green
Green
Green and blue
Green
blue and blue
Blue
General table for calculating the color of a child's eyes, brown eye color is indicated by “K”, green eye color is indicated by “Z” and blue eye color is indicated by “G”:
Eye color
Brown
Brown
Brown
Brown
Brown
Brown
Green
Green
Blue
Using this table, we can say with a high degree of probability that a child will have green eyes if both parents have green eyes or one parent has green eyes and the other has blue eyes. You can also say for sure that the child's eyes will be blue if both parents have blue eyes.
If at least one of the parents has brown eyes, their children may have brown, green or blue eyes.
Statistically:
With two brown-eyed parents, the probability that the child will have brown eyes is 75%, green - 18.75% and blue - 6.25%.
If one of the parents is brown-eyed and the other is green-eyed, the probability that the child will have brown eyes is 50%, green - 37.5%, blue - 12.5%.
If one of the parents is brown-eyed and the other is blue-eyed, the probability that the child will have brown eyes is 50%, blue - 50%, green - 0%.
Thus, if a child’s eyes are not the same color as his parents, there are genetic reasons and justifications for this, because “nothing disappears without a trace and nothing comes out of nowhere.”
To answer the question The gene for brown eyes is considered dominant. Does he always win if the other parent's eyes are not brown? given by the author old-timer the best answer is 3:1, unless I forgot the arithmetic. That is, such parents will have three children with brown eyes, and the fourth with blue eyes. But if the brown-eyed person himself has grandparents with different eye colors, the likelihood that the child will be blue-eyed increases MAYBE....
Answer from Alina[guru]
No not always. Mom's eyes are brown, father's are blue. I have brown ones, my sister has blue ones, and my second sister has green ones. My son's father has brown eyes, that is, both parents have brown eyes, but his son's eye color is green.
Answer from Neurosis[guru]
no, in my opinion this is nonsense... if he doesn’t always win, why is he dominant?
Answer from Accomplice[newbie]
No, no and NO! My mom and dad are brown-eyed, and I have blue eyes! My husband has brown ones, and our children have blue ones! Here!
Answer from Alexey 11[guru]
Unfortunately it is so
Answer from Larisa Pavlova[guru]
no, not always, my eyes are gray and my husband’s are brown, our daughter’s eyes are gray like mine
Answer from EYES GREEN KNEES BLUE[guru]
In our case, the brown one won))) as you know, I have green eyes))
Answer from Diver[active]
not always but often
Answer from N.[guru]
We went through this at school, there are calculations on the power of probability, open the textbook “General Biology”.)
Answer from Yatyana[guru]
I have brown eyes, my husband has blue eyes, but my daughter still has blue eyes like her husband, which means that brown ones do not always dominate
Answer from Olka[newbie]
Not always!! ! A child does not necessarily inherit a dominant gene, but can also inherit a recessive one if it was present in previous generations). And we have brown-eyed parents and a blue-eyed daughter))
Answer from Anna Zilina[active]
won against us. My husband has brown eyes, my daughter also has brown eyes.
Answer from Kisa[expert]
Biology textbook for 9th grade. No not always.
Answer from ~Give me the Crown, Darling~[guru]
not always. my father is brown, and my mother is green
Answer from MarS[guru]
My wife and I have brown eyes, and my daughter has blue eyes, like her grandfather’s. AND.. . such a paradox. Until I was seven years old, my eyes were blue, and then they suddenly turned brown, that is, they became caried-dominated:.... (my father had blue eyes, my mother had brown eyes).
Answer from Irina I[guru]
Not always.
Answer from Hyperv strat[newbie]
We cannot isolate all alleles. Compared to all common alleles, it wins. But what if there is such a gray-brown-crimson color that its allele is more dominant? It's impossible to say for sure.
Answer from Vita[guru]
not always
Answer from Lyubov Semyonova[guru]
My eyes are green, my husband's are brown, and my daughter's are blue.
Answer from [email protected]
[guru]
No. I have brown eyes, but our dad has blue eyes and our daughter has blue eyes.
