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 Brown eyes is a dominant gene
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.
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.”
Blue and green, their inheritance results in two pairs of genes. The shades of these colors are determined by the individual characteristics of the body to distribute 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 light 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, the dominant color in the EYCL 1 allele is green, and blue eyes are inherited in the presence of a recessive trait in two genes. In genetics, it is customary to denote a dominant trait with a capital letter of the Latin alphabet, and a recessive trait is a lowercase letter. If there are uppercase and lowercase letters in a gene, the organism is heterozygous for this trait and exhibits a dominant color, and 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 blue-eyed child 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. For 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 indicates 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. a sign of 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. The presence in the HERC2 gene of the trait of brown eyes of type Aa, and in the EYCL 1 gene of the recessive trait aa, causes light brown eyes. The homozygous trait of green eyes AA at the EYCL 1 locus determines a more saturated color than the heterozygous set Aa.
Problem 1. In humans, the gene for brown eyes is dominant over the gene for blue eyes. What is the probability of having blue-eyed children in a family where the mother had blue eyes and the father had brown eyes, and it is known that he is heterozygous for this trait?
Solution: Let's write down the crossing scheme.
R: ♀ aa x ♂ Aa
blue brown
G: (a) (A) , (a)
brown blue
Answer: the probability of having a blue-eyed child is 50%.
Task 2. Phenylketonuria is inherited as an autosomal recessive trait. In a family where both parents were healthy, a child with phenylketonuria was born. What is the probability that the second child in this family will also be sick?
Solution. R: ♀ A- x ♂ A-
Reasoning. Since both parents are healthy, they can have both the AA and Aa genotypes. Since the first child in this family was sick, his genotype is aa. According to the gamete purity hypothesis, the body receives one allele of a gene from the father, and the other from the mother. Consequently, both parents are heterozygous for the analyzed trait - Aa.
Now you can determine the probability of having a second child with a patient:
R: ♀ Aa x ♂ Aa
Norm norm
G: (A), (a) (A), (a)
F 1: AA, 2 Aa, aa
Normal normal phenylketonuria
Thus, 75% of children will be healthy, and 25% will be sick.
Answer: 25%.
Task 3. In some breeds of cattle, polledness is dominant over hornedness.
A) When crossing polled and horned animals, 14 horned and 15 polled offspring were born. Determine the genotypes of the parental forms.
C) As a result of crossing horned and polled animals, all 30 offspring were polled. Determine the genotypes of the parental forms.
C) Crossing polled animals with each other produced 12 polled and 3 horned calves. Determine the genotypes of the parental forms.
Solution. The genotypes of the parents can be determined by segregation in the offspring. In the first case, the splitting was 1:1, therefore there was an analyzing cross:
R: ♀ Aa x ♂ aa
polled horniness
G: (A), (a) (a)
polled hornedness
In the second case, there was uniformity of the offspring, therefore homozygous horned and polled animals were crossed:
R: ♀ AA x ♂ aa
Norm norm
polled
In the third case, a 3:1 split occurred, which is only possible when crossing two heterozygotes:
R: ♀ Aa x ♂ Aa
polled polled
G: (A), (a) (A), (a)
F 1: AA, 2 Aa, aa
polled hornedness
75% - polled
25% - horned
Answer: A) Aa and aa
B) AA and aa
C) Aa and Aa
Task 4. In humans, brown eyes dominate over blue ones, and right-handedness dominates over left-handedness.
1. What is the probability of having a left-handed, blue-eyed child in a family where the mother is blue-eyed and right-handed (although her father was left-handed), and the father has brown eyes and is predominantly left-handed, although his mother was blue-eyed and right-handed?
2. In a family of brown-eyed, right-handed people, a left-handed child with blue eyes was born. What is the probability that your next child will be right-handed and have blue eyes?
♂--вв ♀ааВ-
R: ♀ aaB- x ♂A-bb
Reasoning. First you need to determine the genotypes of the parents. Since the woman’s father was left-handed, she is therefore heterozygous for the B gene; the man is heterozygous for gene A, since his mother had blue eyes.
Examination. Let's write down the crossing scheme:
R: ♀ aaVv x ♂Aavv
Blue, right Car., lion.
G: (аВ), (ав) (Ав), (ав)
F 1: AaBv, aaBv, Aavv, aavv
Kar., right. Goal, right Kar, lion. Blue, lion
Answer: the probability of having a blue-eyed, left-handed child is 25%.
R: ♀ A-B- x ♂ A-B-
Brown-eyed Brown-eyed
Right-handed right-handed
Blue-eyed lefty
Reasoning. Since, according to the gamete purity hypothesis, the organism receives one gene allele from one parent, and the other from the other, then both parents are heterozygous for both pairs of analyzed genes; their genotype is AaBb.
P: ♀ AaBv x ♂ AaBv
Kar. Right Kar. Right
Thus, the probability of having the next right-handed child with blue eyes (genotype aaBb or aaBB) is 3/16 (or 18.75%).
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 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. 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?
