Two Questions xD?

Question

Mrs. Smith is a carrier for hemophilia. She has one son and one daughter. What is he likelihood that her son has hemophilia? That her daughter is a carrier?

Assume that a father carries an allele for a sex-linked dominant disorder. What is the likilihood that his sons an daughters will in herit the disorder?

Thanks in advance.

Answer 1

In the first question, we'll assume that her husband does not have hemophilia. In that case, her son will inherit one or the other of her X-chromosomes. Consequently, son's have a 50% chance of having hemophilia. Her daughters will also inherit one or the other of her X's (as well as their father's X), and so will have a 50% chance of being a carrier.

Since son's get their 1 X chromosome from their mother, they will have NO chance of getting their father's disorder. Daughters do get their father's X chromosome. Consequently, they WILL ALL have the disorder.