In humans, the gene for brown eyes is dominant over the gene causing blue eyes. A blue-eyed man, one of whose parents had brown eyes,

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 dominates the gene causing blue eyes. A blue-eyed man, one of the parents who had brown eyes, got married

on 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?

No. 2. What kind of offspring can you expect?

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. A guinea pig with shaggy fur
crossed with an individual having 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 for brown eyes
dominates the gene causing
Blue eyes. Blue-eyed man, alone
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 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. Cattle have a 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 for long, coffee-colored hair.
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, dominates the gene,
determining the development of left-handedness. Both
pairs of genes are located in different
chromosomes. What kind of children can they 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, 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, the dominance of brown 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.”

We do not choose the color of our eyes, the shape of our ears and nose - these and many other features are inherited from our parents and distant ancestors, the existence of which we can only guess. The quality of vision, hearing or smell does not depend on the shape of the organ of perception, but family traits are sometimes something like a certificate of membership in a clan. Some families are famous for their tall stature, while in others the “trick” is protruding ears or club feet. The inheritance of eye color is not one of the strictly transmitted traits, but there are still certain patterns.

Eye color: diversity and genetics

There are 7 billion people living on Earth, each of whom has a set of individual traits. The color of the iris is one of the features that remains virtually unchanged in an adult, although in older people it loses its brightness.

Scientists counted several hundred possible shades and classified them. For example, according to the Bunak scale, the rarest are yellow and blue irises. The Martin Schultz scale classifies black eyes as rare. There are also anomalies: in albinos, with a complete absence of pigment, the iris is white. Interesting research on how the unequal color of two eyes is inherited.

Formation of iris color

The iris consists of two layers. In the anterior, mesodermal layer is the stroma, which contains melanin. The color of the iris depends on the distribution of the pigment. The color of the posterior, ectodermal layer is always black. The exception is albinos, who are completely devoid of pigments.

Basic colors:

Blue and cyan

The iris fibers are loose and contain a minimum of melanin. There is no pigment in the shells; reflected scattered light creates the impression of blue. The thinner the stroma, the brighter the azure. Almost all people are born with heavenly eyes; this is the common eye color for all babies. Genetics in humans manifests itself towards the end of the first year of life.

In blue-eyed people, the whitish collagen fibers in the stroma are more densely distributed. The first blue-eyed people appeared on the planet about 10,000 years ago thanks to a gene mutation.

Blue-eyes inhabit mainly the north of Europe, although they are found throughout the world.

Grey

With a high collagen density in the outer layer of the membrane, the iris is gray or blue-gray. Melanin and other substances can add yellow and brown impurities to the color of the iris.

Many gray-eyed people live in the north and east of Europe.

Green

It appears when yellow or light brown pigment and diffused blue or cyan are mixed. With this coloring, many shades and uneven distribution across the iris are possible.

Pure green is very rare. The best chances to see them are in Europe (Iceland and the Netherlands) and Turkey.

Amber

The yellow-brown iris may have a greenish or copper tint. There are very light and dark varieties.

Olive (walnut, green-brown)

The shade depends on the lighting. Formed by mixing melanin and blue. There are shades of green, yellow, brown. The color of the iris is not as uniform as amber.

Brown

If there is a lot of pigment in the iris, a brown color of varying intensity is formed. People with such eyes belong to all races and nationalities; brown-eyed people make up the majority of humanity.

Black

When the concentration of melanin is high, the iris is black. Very often, the eyeballs of black-eyed people are yellowish or grayish. Representatives of the Mongoloid race are usually black-eyed, even newborns are born with an iris saturated with melanin.

Yellow

A very rare phenomenon, it usually occurs in people suffering from kidney disease.

How is eye color inherited?

The inheritance of eye color in humans is beyond doubt among geneticists.

• Light is formed due to a mutation in the OCA2 gene.
• Blue and green - EYCL1 gene of chromosome 19.
• Brown - EYCL2.
• Blue - EYCL3 chromosome 15.
• And the genes SLC24A4, TYR are also involved in formation.

According to the classical interpretation, the heredity of eye color occurs as follows: “dark” genes dominate, and “light” genes are recessive. But this is a simplified approach - in practice, the probability of inheritance is quite wide. The combination of genes determines eye color, but genetics can present unexpected variations.

Eye color is inherited

Almost all human babies are born with blue eyes. Inheritance of eye color in children appears approximately six months after birth, when the iris acquires a more pronounced color. By the end of the first year, the iris is filled with color, but final formation is completed later. In some children, the eye color determined by genetics is established by the age of three or four, while in others it is formed only by ten.

Inheritance of eye color in humans appears in childhood, but with age the eyes may become pale. In old people, pigments lose their saturation due to degenerative processes in the body. Some diseases also affect eye color.

Genetics is a serious science, but it cannot say with certainty what kind of eyes a person will have.

90% of the probability of eye color is determined by hereditary factors, but 10% should be left to chance. Eye color (genetics) in a person is determined not only by the color of the iris of the parents, but also by the genome of ancestors up to the fifth generation.

Eye color (genetics) in a child

The established idea that eye color is literally inherited is erroneous and outdated. A child of a brown-eyed father and mother may well be blue-eyed if one of the grandparents or more distant ancestors had light eyes.

To understand how eye color is inherited, it should be taken into account that each person inherits the genes of his mother and father. In these pairs - alleles, some genes can dominate over others. If we talk about a child’s inheritance of eye color, the “brown” gene is dominant, but the “set” may consist of recessive genes.

Probability of a child's eye color

It can be predicted with a high degree of certainty that the child will be born blue-eyed, but the iris will change with age. It’s definitely not worth drawing conclusions at birth, since the inheritance of eye color in children does not appear immediately.

For many years, geneticists could not come to a common opinion on how eye color is inherited in children. The most convincing hypothesis was that of the Austrian biologist and botanist Gregor Johann Mendel, who lived in the 19th century. The abbot in his teaching, using the example of inheritance of hair color, suggested that dark genes always dominate light ones. Subsequently, Darwin and Lamarck developed the theory and came to a conclusion about how eye color is inherited.

Schematically, the patterns of inheritance of eye color by children can be described as follows:

• Brown-eyed or black-eyed parents will have dark-eyed children.
• If the parents are light-eyed, the child will inherit their eye color.
• A child born to parents with dark and light eyes will inherit a dark (dominant) or medium iris color.

Science, which grew from these observations and generalizations, calculated the heredity of eye color in children as accurately as possible. Knowing how eye color is inherited, you can fairly accurately determine which eyes your descendant will inherit.

How is eye color inherited in children?

There cannot be one hundred percent certainty in one result, but the child’s likely inheritance of eye color can be predicted quite accurately.

Eye color (genetics) in a child:

1. With two brown-eyed parents, a child inherits their eye color in 75% of cases, the probability of getting green is 18%, and blue is 7%.
2. Green and brown eyes of father and mother determine the inheritance of eye color by the child: brown - 50%, green - 37%, blue - 13%.
3. Blue and brown eyes of mom and dad mean that the child should not have green eyes. The child can be brown-eyed (50%) or blue-eyed (50%).
4. For a green-eyed couple, the likelihood of having a baby with brown eyes is very small (1%). Eyes will be green (75%) or blue (24%).
5. A child born from a union of green-eyed and blue-eyed partners cannot have brown eyes. Eye color (genetics) is equally likely to be green or blue.
6. And also a brown-eyed child cannot be born to blue-eyed parents. With 99% accuracy, he will inherit his parents' eyes and there is a small chance that his iris will be green (1%).

Interesting facts about eye color. Genetics in practice

• Most people on Earth have brown eyes.
• Only 2 percent of people look at the world with green eyes. Most of them are born in Turkey, but in Asia, the East and South America they are a real rarity.
• Many representatives of the peoples of the Caucasus have blue eyes.
• Icelanders are a small nation, but most of them are green-eyed.
• Eyes of different colors are an almost unique phenomenon, but this is not a pathology. Multi-colored eyes always attracted attention.
• Grass-colored eyes are often combined with red hair. Perhaps this explains the uniqueness - the Inquisition considered red-haired and green-eyed girls to be witches and mercilessly exterminated them.
• The iris of albinos is practically devoid of melanin; blood vessels are visible through the transparent membrane, so the eyes become red.
• At birth, a person receives eyes of a ready size. The ears and nose continue to grow slowly throughout life, but the eyeballs remain the same.
• All blue-eyed people share a common ancestor. The genetic mutation that resulted in the appearance of the first blue-eyed man appeared 6 to 10 thousand years ago.

It is difficult to predict exactly what the eyes of an unborn child will be like, because it is not always possible to take into account all hereditary factors. The color of the iris can change until the age of ten - this is within normal limits.

Eye color: how it is passed on from parents to child. Calculate the child's eye color.

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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:

(*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 ones come from? HERC2 green eye color - explained below. In the meantime, some data from the general theory of genetics: brown HERC2 - dominant, and blue is recessive, so the carrier has one brown and one blue HERC2 eye color will be brown. However, to his children the bearer of one brown and one blue HERC2 with a 50x50 probability it can transmit both brown and blue HERC2 , that is, the dominance of brown has no effect on the transfer of the copy HERC2 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 to such a woman will be brown-eyed, even if the man has blue or green eyes, since she will pass on one of her two brown genes to the children. But grandchildren can have eyes of any color:

So, for example:

HERC2 about the mother's t is brown (the mother, for example, has both HERC2 brown)

HERC2 from the father - blue (father, for example, has both HERC2 blue)

HERC2 The child has one brown and one blue. The eye color of such a child is always brown; at the same time your HERC2 he can pass on the blue color to his children (who can also receive it from the second parent HERC2 blue and then have eyes either blue or green).

Now let's move on to the gene gay: it comes in green and blue (blue, grey); each person also has two copies: a person receives one copy from his mother, the second from his father. Green gay is the dominant gene, blue gay - recessive. A person thus has either 2 blue genes gay or 2 green genes gay or one blue and one green gene gay . At the same time, this affects the color of his eyes only if he has HERC2 from both parents - blue (if he received brown from at least one of the parents HERC2 , his eyes will always be brown).

So, if a person received blue from both parents HERC2 , depending on the gene gay his eyes can be the following colors:

gay gene: 2 copies	Human eye color
Green and Green	green
Green and blue	green
blue and blue	blue

General table for calculating a child's eye color, brown eye color is designated "K", green eye color is designated "Z" and blue eye color is designated "G":

HERC2	Gey	eye color
QC	ZZ	brown
QC	Zg	brown
QC	GG	brown
Kg	ZZ	brown
Kg	Zg	brown
Kg	GG	brown
yy	ZZ	green
yy	Zg	green
yy	GG

Incredible facts

Researchers have proven that Blue eye color is the result of a genetic mutation that probably occurred between 6,000 and 10,000 years ago. Scientists say they have discovered the reason why some of us have blue pigment in the iris.

Professor Hans Eiberg, leader of the research team at the University of Copenhagen, claims that all humans originally had brown eyes. As a result of a genetic mutation, the color of the eyes has changed, and both of these pigments are present in the iris of the eyes of modern people.

According to experts, most likely blue eye color comes from the countries of the Middle East or the northern part of the Black Sea coast. It was in this area that the largest migration took place during the Neolithic period (about 6,000 - 10,000 years ago). People moved in huge groups to the northern part of Europe.

"These are just our guesses," says Professor Eyberg. According to him, this could also be the territory of the northern part of Afghanistan.

Genetic mutation

This mutation, which occurred thousands of years ago, affected the so-called OCA2 gene and literally, “turned off” the ability of brown eyes to produce dark pigment.

For those less educated on this issue, it is worth explaining that the OCA2 gene is involved in the production of melanin, the pigment that gives color to hair, eyes and skin. A mutation in neighboring genes does not completely immobilize the OCA2 gene, but it certainly limits its action, thereby reducing the production of melanin in the iris. Thus, brown eyes are “diluted” with blue pigment.

If the OCA2 gene were completely turned off, those who inherited this mutation would lose melanin for their skin, hair and iris. Sometimes this happens. We call people with a complete lack of melanin albinos.

Professor Eyberg and his colleagues examined the DNA of blue-eyed people from countries where the majority of the population has brown eyes. Residents of Jordan, India, Denmark and Turkey took part in a number of experimental observations.

The results of Professor Eyberg's research are very important for genetics in general. For the first time in 1996, a scientist suggested that the OCA2 gene is responsible for eye and hair color. From this moment, a very important stage began in the study of the OCA2 gene, as well as all processes in the body associated with this gene.

The results of this study were published in the journal Human Genetics, which clearly indicate that all blue-eyed inhabitants of our planet were once the owners of brown eyes, and only as a result of the mutation that occurred, the pigment of the eyes changed.

Albinism in humans

It is known that the cause of albinism is the absence of the enzyme tyrosinase, which is involved in the normal synthesis of melanin.

There are several main types of this genetic disorder:

1. Oculocutaneous albinism.

2. Temperature-sensitive albinism.

3. Ocular albinism.

Treatment of any of these types is unsuccessful. It is impossible to compensate for the lack of melanin or prevent various visual disorders that are an integral part of the disease.