In humans, the gene for brown eyes dominates over blue eyes, and the ability to use predominantly the right hand dominates over left-handedness. The genes are not linked. A blue-eyed, right-handed man married a brown-eyed, right-handed woman. They had two children: a brown-eyed left-hander and a blue-eyed one.
married a brown-eyed woman whose father had brown eyes and whose mother had blue eyes. What kind of offspring can be expected from this marriage?
In humans, the gene for brown eyes is dominant over the gene causing blue eyes. A blue-eyed man, one of the parents who had brown eyes, got marriedon a brown-eyed woman whose father had brown eyes and his mother had blue eyes. What kind of offspring can be expected from this marriage?
from crossing a cow and a bull,
heterozygous for coat color?
Problem No. 3. Guinea pigs have frizzy hair
wool is determined by a dominant gene, and
smooth - recessive.
1. Crossing two curled pigs between
produced 39 individuals with shaggy fur and
11 smooth-haired animals. How many among
individuals having a dominant phenotype,
must be homozygous for this
sign?
2. Guinea pig with shaggy fur
crossed with an individual with a smooth
wool, gave birth to 28 frizzy and 26
smooth-haired offspring. Define
genotypes of parents and offspring.
Task No. 4. An offspring was obtained at the fur farm
in 225 minks. Of these, 167 animals have
brown fur and 58 bluish-gray minks
coloring. Determine the genotypes of the original
forms, if it is known that the gene is brown
coloring dominates the gene,
defining bluish-gray color
wool
Problem No. 5. A person has a gene brown eyes
dominates the gene causing
Blue eyes. Blue-eyed man, one
of whose parents had brown eyes,
married a brown-eyed woman who
the father had brown eyes, and the mother had blue eyes.
What kind of offspring can be expected from this
marriage?
Problem No. 6. Albinism is inherited in
human as a recessive trait. In the family
where one of the spouses is an albino, and the other has
pigmented hair, have two children.
One child is albino, the other is
dyed hair. What is the probability
birth of the next albino child?
Problems on di- and polyhybrid crossing
Problem No. 8. At a large cattle gene
polledness dominates the horned gene, and
gene for black coat color - above the gene
red color. Both pairs of genes are located
in different pairs of chromosomes.
1. What will the calves turn out to be like if they are crossed?
heterozygous for both pairs
signs of a bull and a cow?
2. What kind of offspring should be expected from
crossing a black polled bull,
heterozygous for both pairs of traits,
with a red horned cow?
Problem No. 9. Dogs have black fur
dominates the coffee, and the short coat
- over the long one. Both pairs of genes are in
different chromosomes.
1. What percentage of black shorthairs
puppies can be expected from crossing two
individuals heterozygous for both traits?
2. The hunter bought a black dog with a short
wool and wants to be sure that it is not
carries genes long hair coffee color.
Which partner according to phenotype and genotype do you need?
select for crossing to check
genotype of the purchased dog?
Problem No. 10. A person has a gene for brown eyes
dominates the gene that determines
development of blue eye color, and the gene
conditioning the ability to better master
right hand, predominates over the gene,
determining the development of left-handedness. Both
pairs of genes are located in different
chromosomes. What kind of children can be if
Are their parents heterozygous?
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 the owner of two blue HERC2s gets green eyes is explained below. In the meantime - some data from general theory 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, the dominance of brown does not in any way affect the transmission of a copy of HERC2 to children.
For example, a wife has eyes brown color, 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, since she will pass on to her children one of her two brown genes. 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 its HERC2 blue color he can pass it on to his children (who can also receive blue HERC2 from their second parent and then have eyes of 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 gene gey or 2 green genes gey or one blue and one green gene gay. 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 eye color of a child, 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 the 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.”
What happens to a child who is heterozygous for eye color? The answer is: he will have brown eyes.
The fact is that a child has one gene that can form large number tyrosinase, and a gene that can form a small amount of tyrosinase. However, a single gene can form relatively more tyrosinase, and it may be enough to turn your eyes brown.
As a result, two parents, one of whom is homozygous for brown eyes and the other homozygous for blue eyes, have children who are heterozygous and at the same time have brown eyes. The gene for blue eyes does not appear.
When a person has two different genes for some physical characteristic at identical locations on a pair of chromosomes and only one gene is expressed, that gene is called dominant. A gene that is not expressed is recessive. In the case of eye color, the gene for brown eyes is dominant to the gene for blue eyes. The gene for blue eyes is recessive to the gene for brown eyes.
It is impossible to tell just by looking at a person whether he is homozygous or heterozygous for brown eyes. Either way, his eyes are brown. One way to say something definitive is to find out something about his parents. If his mother or his father had blue eyes, he must be heterozygous. Another way to know something is to see the color of his children's eyes.
We already know that if a man who is homozygous but has brown eyes marries a woman who is homozygous for brown eyes, they will have children who are homozygous for brown eyes. But what will happen if he marries a heterozygous girl? A homozygous male would only form sperm cells with brown eye genes. His heterozygous wife would produce two types of eggs. During meiosis. since her cells have both a brown eye gene and a blue eye gene, the brown eye gene will travel to one end of the cell and the blue eye gene to the other. Half of the formed eggs will contain the gene for brown eyes, and the other half will contain the gene for blue eyes.
You need to understand that eye color depends not only on the pigment produced. The iris consists of anterior and posterior layers. The color of the eye depends on the distribution of pigments in different layers. In addition, the vessels and fibers of the iris play a role. For example, green eye color is determined by blue or gray the posterior layer of the iris, and the anterior layer contains light brown pigment. The total is green.
The definition of gray and blue eyes is similar, only the density of the fibers of the outer layer is even higher and their shade is closer to gray. If the density is not so high, then the color will be gray-blue. The presence of melanin or other substances produces a small yellow or brownish impurity.
The structure of the black iris is similar to the brown one, but the concentration of melanin in it is so high that the light incident on it is almost completely absorbed.
The chance of a sperm cell fertilizing an egg with the gene for brown eyes or an egg with the gene for blue eyes is therefore 50/50. Half of the fertilized eggs will be homozygous for brown eyes, and half will be heterozygous. But all children will have brown eyes.
Now suppose that both father and mother are heterozygous. Both would have brown eyes, but both would also have the gene for blue eyes. The father would form two kinds of sperm cells, one with the gene for blue eyes and one with the gene for brown eyes. In the same way, the mother would form two types of eggs.
Several combinations of sperm and egg cells are now possible. Suppose one of the sperm cells with the brown eye gene fertilizes one of the eggs with the brown eye gene. The child in this case will be homozygous for brown eyes and will naturally have brown eyes. Suppose that a sperm cell with a gene for brown eyes fertilizes an egg cell with a gene for blue eyes, or a sperm cell with a gene for blue eyes fertilizes an egg cell with a gene for brown eyes. In either case, the child will be heterozygous and will still have brown eyes.
But there is another option. What if a sperm cell with the blue eye gene fertilizes an egg with the blue eye gene?
In this case, the child will be homozygous for blue eyes and will have blue eyes.
Thus, two brown-eyed parents can have a blue-eyed child. A gene that had seemed to disappear appeared again.
Besides, you can tell something about the parents by looking at the child. Although their eyes are brown, just like the homozygous person, you know that they both must be heterozygous, otherwise the gene for blue eyes would not express itself.
Chapter from the book " Races and peoples»
William Boyd "Tsentrpoligraf" 2005
Approximate map of the distribution of blue and green eyes in Europe.
Blue And blue eyes are most common among the European population, especially in the Baltics and Northern Europe. Eyes of these shades are also found in the Middle East, for example, in Afghanistan, Lebanon, Iran.
Grey eye color is most common in Eastern and Northern Europe. It is also found in Iran, Afghanistan, Pakistan and parts of North West Africa.
Purely green eye color is extremely rare. Its speakers are found in Northern and Central Europe, less often - in Southern Europe.
Brown- the most common eye color in the world. It is widespread in Asia, Oceania, Africa, South America and Southern Europe.
Black the type is widespread primarily among the Mongoloid race, in the South, South-East and East Asia.
PSYCHOLOGY
Psychology of sympathy
Appearance is not the only factor on which our attitude towards people depends. When we get to know a person, in addition to his appearance, we immediately notice his other properties that enhance or, conversely, reduce the impression that his appearance made on us.
There are certain established ideas about what it should be like positive person. So, many of us are convinced that a girl should be beautiful and a man should be smart. If you look at it, the requirement is quite cruel: clearly, not all girls are beautiful, just as not all men are very smart (after all, when we say “smart,” we mean that he is smarter than others, smarter than the majority, stands out from the majority). It turns out that we are ready to recognize only some privileged part of our fellow citizens as worthy of attention, defining everyone else an order of magnitude lower. IN everyday life We, of course, don’t think about it, don’t analyze this stereotype so deeply, but it lingers in our consciousness, takes root, and it turns out that getting rid of it is not always easy.
The next circumstance on which the emergence of sympathy depends is the dissimilarity or similarity of the partners. They often say that these people got together because they are similar to each other. They say it no less often. that people got together precisely because they were very different. Depending on the situation, either one or the other is significant.
Blue and green, their inheritance results in two pairs of genes. The shades of these colors are determined individual characteristics The body distributes melanin in chromatophores, which are located in the iris. Other genes that are responsible for hair color and skin tone also affect the shade of eye color. For blond people with fair skin are typical, and representatives of the Negroid race have dark brown eyes.
The gene that is responsible only for eye color is located on chromosome 15 and is called HERC2, the second gene - EYCL 1 is located on chromosome 19. The first gene carries information regarding brown and blue colors, the second - about green and blue.
The dominant color in the HERC2 allele is brown, in the EYCL 1 allele - green, and blue eyes are inherited if there is a recessive trait in two genes. In genetics, it is customary to designate dominant capital letter Latin alphabet, the recessive trait is a lowercase letter. If a gene contains capital letters and lowercase letters- the organism is heterozygous for this trait and has a dominant color, but a hidden recessive trait can be inherited by a child. A “suppressed” trait will appear in a baby when an absolute recessive allele is inherited from two parents. That is, parents may well have a child with blue eyes or with.
Using latin letters, brown eye color, which is determined by the HERC2 gene, can be designated AA or Aa, blue eyes correspond to the set aa. When a trait is inherited, the child receives one letter from each parent. Thus, if dad has a homozygous trait of brown eyes, and mom has blue eyes, then the calculations look like this: AA+aa=Aa, Aa, Aa, Aa, i.e. a child can only achieve the Aa set, which manifests itself according to the dominant, i.e. the eyes will be brown. But if the father is heterozygous and has the Aa set, and the mother is blue-eyed, the formula looks like: Aa+aa=Aa, Aa, aa,aa, i.e. there is a 50% chance that a child with a blue-eyed mother will have the same eyes. U blue-eyed parents the eye inheritance formula looks like: aa+aa=aa ,aa, aa, aa, in this case the baby inherits only the recessive allele aa, i.e. his eye color will be blue.
In the EYCL 1 allele, eye color is inherited in the same way as in the HERC2 gene, but only the letter A denotes green. Nature arranges it in such a way that the existing dominant trait of brown eyes in the HERC2 gene “defeats” the existing green trait in the EYCL 1 gene.
Thus, a child will always inherit brown eye color if one of the parents has a homozygous dominant set of AA in the HERC2 gene. If a parent with brown eyes passes on the recessive gene a to the child, i.e. blue eyes, then the color of the eyes determines the presence of a green dominant trait in the EYCL 1 gene. In cases where a parent with green eyes does not transmit the dominant trait A, but “gives” the recessive allele a, the child is born with blue eyes.
Since eye color is determined by two genes, its shades are obtained from the presence of undetected characteristics. If a child has the AA genetic set in the HERC2 allele, then the eyes will be dark brown. Presence of the trait in the HERC2 gene brown eyes by type Aa, and in the EYCL 1 gene of the recessive trait aa, causes light brown eyes. Homozygous trait green eyes AA in the EYCL 1 locus determines a more saturated color than the heterozygous set Aa.
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 over 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 is sick 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 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?
