home Calculators The dominant eye color is blue or brown. Inheritance of eye color in humans: formation and patterns. Curious facts about eye color. Genetics in practice

The dominant eye color is blue or brown. Inheritance of eye color in humans: formation and patterns. Curious facts about eye color. Genetics in practice

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 on different pairs of chromosomes.
What is the probability of having a sick child if both parents are diheterozygous?

4) The black suit gene in cats is sex-linked. Another allele of this gene corresponds to the red color, heterozygous animals have a spotted ("tortoiseshell") color.
What will be the offspring from crossing a "tortoiseshell" cat with a red cat?

5) The forensic medical examination was tasked with finding out whether the boy in the family is a native 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 basis is it based?

6) When crossing a brown dog with white, all offspring are white. When breeding the resulting offspring "in itself" 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 parents and offspring?

7) In chickens, the color stripe 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 chickens: a striped cockerel with a comb and a striped hen without a comb. Indicate the genotypes of parental forms and offspring.

1) In humans, the curly hair gene (A) dominates the smooth gene (a), and the normal hearing gene (B) dominates the deaf-mute gene (c). In a family where parents are good

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 that such a family will have a deaf child with curly hair?

2) The brown eye gene dominates the blue eye gene. 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 offspring can be expected from this marriage?

in humans, the gene for brown eyes dominates in humans, the gene for brown eyes dominates over the gene that determines the blue color of the eyes, and the gene that determines the ability to better

owning the right hand prevails over the gene for left-handedness. What is the probability of the birth of blue-eyed left-handed children from the marriage of two diheterozygous parents?

in humans, the gene for brown eyes dominates the gene for blue eyes, a blue-eyed man, one of whose parents has brown eyes, marries

a brown-eyed woman whose father has brown eyes and whose mother is blue. What 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

brown. What offspring can be expected from this marriage, if it is known that the brown eye gene dominates the blue eye gene?
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 had 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?

What happens to a child who is heterozygous for eye color? The answer is: he will have brown eyes.

The fact is that the child has one gene that can form a large amount of tyrosinase, and a gene that can form a small amount of tyrosinase. However, a single gene can generate a relatively large amount of tyrosinase, and it may be enough to color the eyes brown.

As a result, two parents, one 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 blue eye gene 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 does not show up is recessive. In the case of eye color, the brown eye gene is dominant over the blue eye gene. The blue eye gene is recessive to the brown eye gene.

It is impossible to tell just by looking at a person whether they are homozygous or heterozygous for brown eyes. Either way, his eyes are brown. One way to say something definite 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 homozygous brown-eyed man marries a homozygous brown-eyed woman, they will have homozygous brown-eyed children. But what happens if he marries a heterozygous girl? A homozygous male would only form sperm cells with genes for brown eyes. 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 - the gene for blue eyes.

It must be understood 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 nature of the distribution of pigments in different layers. In addition, the vessels and fibers of the iris play a role. For example, the green color of the eyes is determined by the blue or gray color of the back layer of the iris, and the light brown pigment is distributed in the front layer. 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 gives a slight 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 falling on it is almost completely absorbed.

The chance of a sperm cell fertilizing a brown-eyed egg or a blue-eyed egg is thus 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 at the same time have the gene for blue eyes. The father would form two kinds of sperm cells, one with the blue eye gene and the other with the brown eye gene. In the same way, the mother would form two kinds 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. Let us suppose that a sperm cell with the gene for brown eyes fertilizes an egg with the gene for blue eyes, or a sperm cell with the gene for blue eyes fertilizes an egg with the gene for brown eyes. Either way, the baby will be heterozygous and still have brown eyes.

But there is another option. What if a sperm cell with a blue eye gene fertilizes an egg with a 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. The gene that seemed to have vanished reappeared.

In addition, you can, by looking at the child, say something about the parents. Although their eyes are brown, just like a homozygous person, you know that they both must be heterozygous or the blue eye gene would not show up.

Chapter from the book Races and peoples»

William Boyd Centerpolygraph 2005

An approximate map of the distribution of blue and green eyes in Europe.

Blue And blue eyes are most common among the population of Europe, 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 Northwest Africa.

Purely green eye color is extremely rare. Its carriers are found in Northern and Central Europe, less often in Southern Europe.

Brown- the most common eye color in the world. It has a ubiquitous distribution in Asia, Oceania, Africa, South America and Southern Europe.

Black the type is distributed primarily among the Mongoloid race, in South, Southeast and East Asia.

PSYCHOLOGY

The psychology of sympathy

Appearance is not the only factor on which our attitude towards people depends. When we get to know a person, then, in addition to appearance, we immediately note his other properties that enhance or, conversely, reduce the impression that his appearance made on us.

There are certain preconceived notions about what a positive person should be like. 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: it is clear that 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 most, singled out from the majority). It turns out that we are ready to recognize as worthy of attention only some privileged part of fellow citizens, defining all the rest an order of magnitude lower. In everyday life, of course, we don’t think about it, we don’t analyze this stereotype so deeply, but it lingers in the mind, takes root, and getting rid of it, it turns out, is not always easy.

The next circumstance on which the emergence of sympathy depends is the dissimilarity or similarity of partners. It is often said that these people came together because they are similar to each other. No less frequently spoken. that people came together just because they are very different. Depending on the situation, either one or the other is significant.

A question that many parents ask. However, it is impossible to answer this question unambiguously, since the answer depends on 90% of the genetic predisposition and 10% on the case.

Only one thing is clear here - the baby will be born with unclear gray-blue or dark brown eyes.

What color will my child's eyes be?

Almost always, the eyes of newborns have exactly the blue color, which subsequently, starting from 6 months, begins to change and darkens as it is exposed to sunlight (although in most children this happens between the ages of 6 months and a year). By about three or four years of age, a child's eyes acquire their permanent, lifelong color.

Predicting the color of a child's eyes

Below is a diagram that shows the “chances of success” of a particular eye color (in % ratio) depending on the color of the eyes of the parents.

Also look at the site - determining the color of the child's eyes by the color of the eyes of the baby's parents and the color of the eyes of your parents. This is an English-language resource, but it will not be difficult to figure out what's what.

How reliable is this? Let's check together! Please unsubscribe in the comments if the color of the eyes in reality coincided with the predictions calculated and proposed by these methods.

Inheritance of eye color in terms of genetics

The color of a child's eyes is determined by parental genes, but great-grandparents also contribute to the baby's appearance. It turns out that their colors and shades have a polygenic nature of inheritance and are determined by the amount and types of pigments in the iris cornea.

In general, the color of a person's eyes depends on the amount of melanin in the iris of the eye (melanin is also responsible for the color of our skin). In the spectrum of all kinds of colors, one extreme point will be the blue color of the eyes (the amount of melanin is minimal), and the other is brown (the maximum amount of melanin). People with different eye colors fall somewhere in between these extremes. And the gradation depends on the genetically determined amount of melanin in the iris.

Genetic studies show that the pigment component of the iris is controlled by 6 different genes. They interact with each other according to certain clear patterns, which ultimately leads to a wide variety of eye colors.

There is an established opinion that the color of a child's eyes is inherited according to Mendel's laws - eye color is inherited in almost the same way as hair color: dark color genes are dominant, i.e. the distinctive features (phenotypes) encoded by them take precedence over the distinctive features encoded by the lighter color gene.

Parents with dark hair are more likely to have children with dark hair; offspring of fair-haired parents will be fair-haired; and the child of parents whose hair color is different will have hair whose color will be somewhere in the middle between the parents.

However, the idea that brown-eyed parents can only have brown-eyed children is a fairly common misconception. A brown-eyed couple may well have a blue-eyed child, especially if one of the close relatives has a different eye color). The fact is that a person copies two versions of the same gene: one from the mother, the other from the father. These two versions of the same gene are called alleles, with some alleles in each pair being dominant over others. When it comes to the genes that control eye color, brown will be dominant, however, a child can receive a recessive allele from either parent.

We note some patterns in the inheritance of eye color by a child:

Your husband and you both have blue eyes - 99%, as a child, they will be exactly the same color or light gray. Only 1% gives the chance that your baby will become the owner of green eyes.
If one of you has blue eyes and the other green, then the chances of both eye colors in the child are equalized.
If both parents have green eyes, then 75% of the baby will have green eyes, 24% blue and 1% brown eyes.
The combination of blue and brown eyes in parents gives a 50% to 50% chance for a child to have one or another color of his eye.
Brown and green parental eyes are 50% brown children's eyes, 37.5% green eyes and 12.5% blue.
Both parents have brown eyes. Such a combination in 75% of cases will give the same color to the baby, in 19% - green, and only in 6% of the babies can be blue-eyed.

Some fun facts about eye color

The most common eye color in the world is brown.
The rarest eye color is green - less than 2% of the world's population.
Turkey has the highest percentage of citizens with green eyes, namely: 20%.
For the inhabitants of the Caucasus, the blue eye color is the most characteristic, not counting amber, brown, gray and green. Also, more than 80% of the inhabitants of Iceland have either blue or green eyes.
There is such a thing as heterochromia (from the Greek ἕτερος - “other”, “different”, χρῶμα - color) - different color of the iris of the right and left eyes or uneven coloration of different parts of the iris of one eyes.

Now you know what color your child's eyes will be, and we, in turn, wish that, regardless of color, there would be only happiness and joy in your favorite eyes!

When asked, the gene for brown eyes is considered dominant. Does he always win if the second parent has non-brown eyes? given by the author old-timer the best answer is 3:1 if I haven't forgotten the arithmetic. That is, such parents will have three children with brown eyes, and the fourth with blue eyes. But if the brown-eyed one himself has progenitors with different eye colors, the probability that the child will be blue-eyed MAYBE increases ....

Answer from Alina[guru]
No not always. Mom has brown eyes, dad has blue. I have brown, my sister has blue, my second sister has green. My son's father has brown eyes, meaning both parents have brown eyes, but my son's eyes are green.

Answer from Neurosis[guru]
no, in my opinion it's nonsense ... if it doesn't always win, why is it dominant then?

Answer from Accomplice[newbie]
No, no and NO! My mom and dad are brown-eyed, and I have blue eyes! My husband has brown, and our children with blue! 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 has hazel eyes, our daughter has gray eyes like mine

Answer from EYES GREEN KNEES BLUE[guru]
In our case, brown won))) I have green eyes, as you know))

Answer from diver[active]
not always but often

Answer from N.[guru]
They went through this at school, there are calculations on the degree of probability, open the textbook "General Biology".)

Answer from Yatiana[guru]
my husband has blue eyes, but my daughter still looks like a husband with blue eyes, 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 it can also inherit a recessive one if it was in previous generations). And we have brown-eyed parents-blue-eyed daughter))

Answer from Anna Zhilina[active]
we won. My husband has brown eyes, and my daughter also has brown eyes.

Answer from Kisa[expert]
Biology textbook for grade 9. No not always.

Answer from ~Give me the crown, honey~[guru]
not always. my father has brown and my mother has green

Answer from MarS[guru]
My wife and I have brown eyes, and my daughter's are blue, like her grandfather's. AND.. . such a paradox. Until the age of seven, my eyes were blue, and then they sharply turned brown, that is, cariodominated :) .... (father's eyes were blue, mother's were brown).

Answer from Irina I[guru]
Not always.

Answer from Hyperv strat[newbie]
We cannot isolate all alleles. Compared to all common alleles - wins. But suddenly there is such a gray-brown-crimson color that its allele is more dominant? Can't say for sure.

Answer from vita[guru]
not always

Answer from Lyubov Semenova[guru]
My eyes are green, my husband's are brown, my daughter's are blue.

Answer from [email protected] [guru]
No. I have brown eyes, my dad has blue eyes and my daughter has blue eyes.

Question: In humans, the gene for brown eyes dominates over blue eyes, and the ability to use predominantly the right hand over left-handedness. The genes are not linked. A blue-eyed right-handed man married a brown-eyed right-handed man. They had two children: a brown-eyed left-hander and a blue-eyed right-hander. Determine the probability of the birth in this family of blue-eyed children, owning mainly the left hand.

In humans, the gene for brown eyes dominates over blue eyes, and the ability to use predominantly the right hand over left-handedness. The genes are not linked. A blue-eyed right-handed man married a brown-eyed right-handed man. They had two children: a brown-eyed left-hander and a blue-eyed right-hander. Determine the probability of the birth in this family of blue-eyed children, owning mainly the left hand.

Answers:

Phenotype gene genotype brown A AA,Aa blue a aa right-handed B BB, BB left-handed cc solution P ,aaBv,aavv kar kar gol gol kar kar gol gol pr pr pr pr leo pr leo Answer: the probability of having a blue-eyed left-hander is 1/8 or 12.5%

Given: A --- brown eyes AA, Aa а --- blue eyes aa B --- right-handedness BB, Bb b --- left-handedness bb Find: the probability of birth in this family of blue-eyed children who use predominantly the left hand --- ? Solution: R: ♀AaBb x ♂aaBb G: AB aB Ab ab aB ab F₁: AaBB --- brown eyes; right-handedness; AaBb --- brown eyes; right-handedness; aaBB --- blue eyes; right-handedness; aaBb --- blue eyes; right-handedness; AaBb --- brown eyes; right-handedness; Aabb --- brown eyes; left-handedness; aaBb --- blue eyes; right-handedness; aabb --- blue eyes; left-handedness; ----1/8 * 100% = 12.5% Answer: the probability of birth in this family of blue-eyed children who predominantly use the left hand --- 12.5%.