What are the possible crosses of the following offspring?
Answer
The pedigree below shows the genetic makeup of individuals in this family for cystic fibrosis, an autosomal recessive disease. The father, John, has cystic fibrosis, while the mother, Sally, does not. Of the children, Jack, Liz, and Jean have cystic fibrosis, while Don does not. John's mother does not have cystic fibrosis, but his father does. Toggle over to the image listed under file.
1. What must John's genotype be?
a. AA
b. Aa
c. aa
2. What must John's mother's genotype be?
a. AA
b. Aa
c. aa
3. Sally must have a genotype of:
a. AA
b. Aa
c. aa
4. If Jean and Jim (normal non-carrier) have children, what is the probability that their sons will have cystic fibrosis?
a. 0%
b. 25%
c. 50%
d. 100%