haemophilia is a sex linked recessive trait in humans .if a dather7and son are both haemophilic, but the mother is normal her genotype must be a) Xh Xh b) XH Xh c) XX d ) An Y
Answers
Answer:
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Explanation:
1. A man with hemophilia (a recessive, sex-linked blood clotting disorder) has a daughter of normal phenotype. She marries a man who is normal for the trait.
XH - normal
Xh - hemophilia
Since this is a recessive disorder, one XH allele will give a normal phenotype. When the offspring do not have a XH and only have the Xh allele/alleles they will have the hemophilia condition.
Man's genotype is XhY.
Daughter's genotype is XHXh (She got the Xh from her father. She has a normal phenotype, so we know her other allele is XH.
Daughter's Husband is XHY (Man is normal for the hemophilia trait)
A) What is the probability that a daughter of this mating with be a hemophiliac?
XH
Xh
XH
XH XH
XHXh
Y
XHY
XhY
The probability that a daughter of this mating with be a hemophiliac is zero. Although, there is a 50% chance that a daghter will be a carrier.
B) What is the probability that a son will be a hemophiliac?
The probability that a son will be a hemophiliac is 1/2 or 50%.
C) If the couple has four sons, what is the probability that all four will be born with hemophilia.
Each occurrence has a 1/2 chance of happening.
1/2 x 1/2 x 1/2 x 1/2 = 1/16