3. Extensions to Mendelian Inheritance

Which of the following gametes cannot be formed from the genotype AaBBCc?

Which of the following gametes cannot be formed from the genotype DDeeFfGG?

Which of the following gametes cannot be formed from the genotype HhJjKK?

A pure-breeding tall plant producing oval fruit as described in Problem 2 is crossed to a pure-breeding short plant producing round fruit.

If the F₁ identified in part (a) are crossed to one another, what proportion of the F₂ are expected to be short and produce round fruit? What proportion are expected to be tall and produce round fruit?

A pure-breeding tall plant producing oval fruit as described in Problem 2 is crossed to a pure-breeding short plant producing round fruit.

The F₁ are crossed to short plants producing oval fruit. What are the expected proportions of progeny phenotypes?

In tomato plants, purple leaf color is controlled by a dominant allele A, and green leaf by a recessive allele a. At another locus, hairy leaf H is dominant to hairless leaf h. The genes for leaf color and leaf texture are separated by 16 m.u. on chromosome 5. On chromosome 4, a gene controlling leaf shape has two alleles: a dominant allele C that produces cut-leaf shape and a recessive allele c that produces potato-shaped leaves.

Fully explain the number and frequency of each phenotype class.

In tomato plants, purple leaf color is controlled by a dominant allele A, and green leaf by a recessive allele a. At another locus, hairy leaf H is dominant to hairless leaf h. The genes for leaf color and leaf texture are separated by 16 m.u. on chromosome 5. On chromosome 4, a gene controlling leaf shape has two alleles: a dominant allele C that produces cut-leaf shape and a recessive allele c that produces potato-shaped leaves.

The cross of a purple, hairy, cut plant heterozygous at each gene to a green, hairless potato plant produces the following progeny:

Give the genotypes of parental and progeny plants in this experiment.

The ABO blood group assorts independently of the rhesus (Rh) blood group and both assort independently of the MN blood group. Three alleles, I^A, I^B, and i, occur at the ABO locus. Two alleles, R, a dominant allele producing Rh+, and r, a recessive allele for Rh-, are found at the Rh locus, and codominant alleles M and N occur at the MN locus. Each gene is autosomal.

A man with blood types B, Rh+, and N says he could not be the father of a child with blood types O, Rh−, and MN. The mother of the child has blood types A, Rh+, and MN. Is the man correct? Explain.

The ABO blood group assorts independently of the rhesus (Rh) blood group and both assort independently of the MN blood group. Three alleles, I^A, I^B and i, occur at the ABO locus. Two alleles, R, a dominant allele producing Rh+, and r, a recessive allele for Rh-, are found at the Rh locus, and codominant alleles M and N occur at the MN locus. Each gene is autosomal.

What proportion of children born to a man with genotype I^AI^B Rr MN and a woman who is I^Ai Rr NN will have blood types B, Rh- , and MN? Show your work.

The ABO blood group assorts independently of the rhesus (Rh) blood group and both assort independently of the MN blood group. Three alleles, I^A, I^B and i, occur at the ABO locus. Two alleles, R, a dominant allele producing Rh+, and r, a recessive allele for Rh-, are found at the Rh locus, and codominant alleles M and N occur at the MN locus. Each gene is autosomal.

A child with blood types A, Rh−, and M is born to a woman who has blood types O, Rh−, and MN and a man who has blood types A, Rh+, and M. Determine the genotypes of each parent.

In rats, gene B produces black coat color if the genotype is , but black pigment is not produced if the genotype is bb. At an independent locus, gene D produces yellow pigment if the genotype is D-, but no pigment is produced when the genotype is dd. Production of both pigments results in brown coat color. If neither pigment is produced, coat color is cream. Determine the genotypes of parents of litters with the following phenotype distributions.

9 black, 7 brown

In rats, gene B produces black coat color if the genotype is , but black pigment is not produced if the genotype is bb. At an independent locus, gene D produces yellow pigment if the genotype is D-, but no pigment is produced when the genotype is dd. Production of both pigments results in brown coat color. If neither pigment is produced, coat color is cream. Determine the genotypes of parents of litters with the following phenotype distributions.

3 brown, 3 yellow, 1 black, 1 cream

Syntenic genes can assort independently. Explain this observation.

In rats, gene B produces black coat color if the genotype is , but black pigment is not produced if the genotype is bb. At an independent locus, gene D produces yellow pigment if the genotype is D-, but no pigment is produced when the genotype is dd. Production of both pigments results in brown coat color. If neither pigment is produced, coat color is cream. Determine the genotypes of parents of litters with the following phenotype distributions.

4 brown, 4 black, 4 yellow, 4 cream

In the rats identified in Problem 10, a third independently assorting gene involved in the determination of coat color is the C gene. At this locus, the genotype C– permits expression of pigment from genes B and D. The cc genotype, however, prevents expression of coat color and results in albino rats. For each of the following crosses, determine the expected phenotype ratio of progeny.

BbDdCC×BbDdCC