Question

Duchenne muscular dystrophy (DMD) is a recessive, sex-linked disorder carried on the X chromosome. If a woman who is a carrier of DMD and a man without the disorder have children, which outcome is possible?

a. All of their sons and half of their daughters could have DMD.
b. Half of their sons and half of their daughters could have DMD.
c.Half of their sons and none of their daughters could have DMD.
d. None of their sons and half of their daughters could have DMD.

Answer 1

Answer:D

Step-by-step explanation:

I think it is D because only the mother had it and not the father. I don't think the father could get DMD through sex either. So I think that none of their sons and half the daughters could have DMD because they inherited it from the mother.

Answer 2

C. Half of their sons and none of their daughters could have DMD.

Step-by-step explanation:

DMD is a recessive disorder carried on the X chromosome and it is sex-linked. This means that the gene for DMD is located on the X chromosome and it affects mostly males.

If a woman is a carrier of DMD, it means that she has one copy of the mutated gene and one normal copy, and she does not show any symptoms of the disorder.

If a man without the disorder has children with this carrier woman, half of their sons will inherit the mutated X chromosome from the mother. Therefore, they will have the disorder and half of their sons could have DMD.

Since, Females have two X chromosomes, and therefore, if a daughter inherits the mutated X chromosome from the mother, the second X chromosome will be normal which will help in compensating the effects of the mutant one, hence they will be carrier of the disorder but will not show any symptoms. So none of their daughters could have DMD.

So, the outcome is: C. Half of their sons and none of their daughters could have DMD.