a. b. c. d. all questions binism is a sex-linked inherited condition. Albinism r
ID: 198714 • Letter: A
Question
a. b. c. d. all questions
binism is a sex-linked inherited condition. Albinism results in an absence of pigment melanin in the cyes, skin, and hair. This condition is transmitted as a recessive trait on the X chromosome. Suppose that a woman with the condition marries a man without this trait. What are the genotypes of the man and woman? Construct a Punnett square to determine the offspring for this couple. a. b. What is the probability that they have a child with normal pigmentation? What is the probability that they will have a girl who has albinism? c. d. n ComplectExplanation / Answer
Albinism is a sex linked recessive trait, so in female it will only express when both the X chromosome will carry the t females with albinism trait in one X-chromosome will not show the phenotype. Whereas, as males have one X chromosome, so if this is effected they will show the phenotype of albinism.
Lets assume the chromosome which contain the trait for albinism is Xa
According to the information, the female have the condition, so the genotype is Xa Xa
whereas, the male is normal , so the genotype is XY
now the cross will be- Xa Xa X XY
a) genotype of the female is Xa Xa
genotype of the male is XY
b)
Xa
Xa
X
Xa X
Xa X
Y
XaY
XaY
c) as two of their children have the genotype is Xa X
meaning that they have the trait expressed only in one X.chrosome, this they will show normal pigmentation. So the probability is 1/2 or 50% that they will show normal pigmentation.
d) As both of the girls receive one X chromosome from mother ( which is Xa ) and one X chrosome fro father (X), so they will always express the genotype Xa X, meaning there is no probability of girls who will show albinism. Girls aöways will show normal pigmentation as one of their X chromosome is normal.
Xa
Xa
X
Xa X
Xa X
Y
XaY
XaY
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