A couple has just learned that their daughter has hemophilia. They already have a son who does not have the disease. What are the genotypes of the couple?

I don't know how to do this please help!

#its7thgradeElina

The gene for hemophilia is sex-linked, a recessive on the X-chromosome. The daughter must have both Xs with the gene, while the son does not have the gene on his X chromosome.

With that information, you should be able to get the parental genotypes.

To determine the genotypes of the couple, we need to understand the inheritance pattern of hemophilia. Hemophilia is an X-linked recessive disorder, which means that the mutated gene responsible for the disorder is located on the X chromosome.

Now, in humans, females have two X chromosomes (XX) while males have one X and one Y chromosome (XY). In this case, since the couple already has a son who does not have hemophilia, it means that the father does not have the mutated gene since he cannot pass it on to his son.

The mother, however, must be a carrier of the hemophilia gene because she has passed it on to her daughter. A carrier is a female who has one normal X chromosome and one X chromosome with the mutated hemophilia gene.

Therefore, we can determine the genotypes of the couple as follows:

Father: XY (non-carrier)
Mother: XhX (carrier, where X is the normal gene and Xh is the gene for hemophilia)

Please note that uppercase letters represent dominant genes or non-mutated genes, while lowercase letters represent the recessive genes or the mutated ones.