GN 301 Homework 6: Autosomal Pedigrees and Mendelian Genetics

Assume that there is complete dominance and complete penetrance at each locus and that epistasis does not occur. (These are the same conditions we used in class). Write your answers in numeric form (not in words).

Referring to the cross DdFFGghhRrTt x DDffGgHhRRTt:

How many different gametes does the DdFFGghhRrTt parent produce?

16

How many different genotypes are found among the progeny of this cross?

72

How many different phenotypes are found among the progeny of this cross?

8

What is the probability that the first offspring from this cross will show the dominant phenotype for all loci? (Type in as a decimal and round to 6 digits.)

0\.28125

What is the probability that the first offspring from this cross will be heterozygous for all loci? (Type in as a decimal and round to 6 decimal digits.)

0\.03125

What is the probability that the first offspring from this cross will be a son with genotype DDFfGghhRrTt? (Type in as a decimal and round to 6 decimal digits). Answer

0\.015626

Shaded individuals in this pedigree have an autosomal genetic disorder that causes black teeth. Individuals who are not shaded have the normal white teeth. Please answer the following questions regarding this pedigree. Assume that a capital "B" represents the dominant allele and that a lower case "b" represents the recessive allele.

Which allele is dominant? Answer

White

The twins in this pedigree are

dizyogtic

Which are the pedigree identity numbers of the two related individuals who are parents of a daughter?

III-1 and III-2

The genotype of individual I-4 is

bb

The phenotype of individual II-5 is

White

What is the probability that individual II-1 is heterozygous?

0\.67

What is the probability that the next child from the marriage of II-4 x II-5 will have black teeth?

1/2

Supposed individuals III-1 and III-4 marry and have children. What is the probability that their first child will be a son with white teeth?

3/8

Shaded individuals in the pedigree below have an autosomal disorder that results in a red nose instead of the normal color. Assume that the capital letter represents the dominant allele.

Is the shaded trait dominant or recessive?

Dominant

What is the genotype of individual II-2?

rr

Which two individuals are monozygotic twins?

III-7 and III-8

What is the phenotype of the proband?

Red Nose

What is the probability that a child from a marriage between individuals IV-1 and IV-2 will have a red nose?

1/2

What is the probability that III-4 is heterozygous?

2/3