if you know that a woman is hemophiliac,what can you infer about the genes carried by her parents?

Answer 1

Since hemophilia is a recessive trait found on the X-chromosome, then the woman got the allele for hemophilia from both of her parents.

Her mother was most like Xh XH because the hemophilia allele is fairly rare in the population, and it's not likely that her mother was homozygous for hemophilia. Also, any woman of an age to have a grown child probably would not have survived if she had had hemophilia in the days before treatment with Factor VIII and all. So we can assume that her mom is a carrier.

Her father had hemophilia. XhY. He passed the Xh to his daughter.

Answer 2

Females possess two X-chromosomes, whereas males have one X and one Y chromosome. Since the mutations causing the disease are recessive, a woman carrying the defect on one of her X-chromosomes may not be affected by it, as the equivalent allele on her other chromosome should express itself to produce the necessary clotting factors. However the Y-chromosome in men has no gene for factors VIII or IX. If the genes responsible for production of factor VIII or factor IX present on a male's X-chromosome is deficient there is no equivalent on the Y-chromosome, so the deficient gene is not masked by the dominant allele and he will develop the illness.

Since a male receives his single X-chromosome from his mother, the son of a healthy female silently carrying the deficient gene will have a 50% chance of inheriting that gene from her and with it the disease; and if his mother is affected with haemophilia, he will have a 100% chance of being a haemophiliac. In contrast, for a female to inherit the disease, she must receive two deficient X-chromosomes, one from her mother and the other from her father (who must therefore be a haemophiliac himself)

Answer 3

The father is hemophiliac, and the mother is a carrier (that means her mother was a carrier, or her father was hemophiliac) or a hemophiliac as well.

Answer 4

It is an x-linked recessive trait. A daughter gets an x from her mother and her father, so her father would have to have the disorder and her mother would have to alteast be a carrier. So. the father would be homozygous recessive and the mother would be atleast heterozygous, though she could be homozygous recessive as well.