Answer to Question #154941 in Genetics for GTA

Question

in humans, the left chin trait is dominant to the smooth chin trait. a man who is heterozygous for cleft chin and a woman who has smooth chin decide to have chldren. what fraction of their children are predicted to have a smooth chi.

Answer 1

Let the gene for creft chin be represented by letter A,

The recessive allele (smooth chin) will therefore be a.

Father Mother

Parental genotypes: Aa x aa

gametes A a a a

F1 generation (children)

genotypes: Aa, Aa, aa, aa

Children phenotypes : Creft chinned smooth chinned

Proportion with smooth chin = $\dfrac{2}{4} = \dfrac{1}{2}$