Refer to the pedigree below for this question Individuals wh

Refer to the pedigree below for this question. Individuals who are shaded have the autosomal recessive disorder. Since it is a rare disorder, assume that anyone entering the pedigree (someone whose parents are not in the pedigree) is homozygous, unless there is evidence to the contrary. Those who are not shaded show the dominant phenotype. Let A and a represent the dominant and recessive alleles, respectively. Fill in the table below to indicate the genotype or probability function for the genotype of each individual. Give all probabilities as fractions that are simplified to the lowest value. Type your fractions in #/# format without spaces. For example, one-half should be entered as 1/2 Failure to correctly follow these directions will result in your answer being marked as incorrect.

Fill in the table below to indicate the genotype or the genotype probability of the individual. Two are completed as examples.

Individual

Suppose that III-3 and III-8 have a child. What is the probability that their first child is genotype Aa?

Solution

P(all female)= 1/2 x 1/2 x 1/2 = 1/8
P(all male ) = 1/2 x 1/2 x 1/2 = 1/8
P(all one gender) = P(all female) + P(all male) = 1/8 + 1/8 = 1/4