Question

PLEASE HELP BY TONIGHT: The ability to taste phenylthiocarbamide (PTC) is controlled in humans by a single dominant allele (T). A woman who is a nontaster married a man and they had three children, two boy tasters and a girl nontaster. All the grandparents were tasters. Create a pedigree of this family of this trait. Solid symbols should signify nontasters. Where possible, indicate whether the tasters are TT or Tt.

Answer 1

Here is a possible pedigree for this family:

T
/ \
T T
/ / \
T T t
/ / /
T T t

In this pedigree, the woman who is a nontaster is represented by a solid circle, and the man is represented by an open circle. The two boy tasters are represented by open squares, and the girl nontaster is represented by a solid square. The grandparents are represented by open triangles.

In this pedigree, the man and both of his parents are tasters, so they are likely to be TT genotypes. The woman and her parents are nontasters, so they are likely to have a genotype of tt. The two boy tasters are likely to have a genotype of Tt, and the girl nontaster is likely to have a genotype of tt.