Thomas suffers from a sex-linked blood-clotting disorder called hemophilia that is transmitted by a recessive gene.Neither his mother nor his father has ever shown symptoms of this disease.What can we conclude about the genetic makeup of John's parents?

A) Both the mother and the father have the faulty gene.
B) The mother is a carrier for hemophilia, while the father does not have the gene.
C) The mother is homozygous for the faulty gene, while the father is heterozygous.
D) The father has the faulty gene, while the mother does not.

Question

MARIA AVGI KALAMPALIKI · Accepted Answer

Final Answer : B, Explanation :  Since hemophilia is a sex-linked disorder, it is more likely that the mother is a carrier of the faulty gene on one of her X chromosomes. The father cannot be a carrier because he only has one X chromosome, so if he had the faulty gene he would definitely have the disease. Therefore, it is likely that the father does not have the faulty gene, and is not affected by hemophilia.

Definitions

Learning Objectives

Learning Objectives

Related questions