Hemophilia, a blood clotting disorder in humans, is due to an X-chromosome mutation. What will be the results of mating between a normal (non-carrier) female and a hemophiliac male?

Question

(Hint: this is a sex-linked trait)

a
Half of daughters are normal and half of sons are hemophiliac.
b
All sons are normal, and all daughters are carriers (heterozygous).
c
Half of sons are normal and half are hemophiliac; and all daughters are (heterozygous).
d
All daughters are normal, and all sons are carriers (heterozygous).

Answer 1

To determine the results of mating between a normal (non-carrier) female and a hemophiliac male, we need to consider the genetics involved in sex-linked traits.

1. Genotype of the individuals:

   • The normal (non-carrier) female has the genotype X^NX^N (where X^N represents the normal allele).
   • The hemophiliac male has the genotype X^hY (where X^h represents the hemophilia allele and Y represents the male chromosome).

2. Possible gametes:

   • The normal female can contribute either X^N (normal) gametes.
   • The hemophiliac male can contribute either X^h (hemophilia) or Y (male) gametes.

3. Possible offspring combinations:

   • Female offspring can be X^N from the mother and X^h from the father, resulting in genotype X^NX^h (carrier).
   • Male offspring can be X^N from the mother and Y from the father, resulting in genotype X^NY (normal).

4. Results:

   • All daughters will be X^NX^h (carriers).
   • All sons will be X^NY (normal).

Based on this analysis, the answer is:

b. All sons are normal, and all daughters are carriers (heterozygous).