Exam 4: Gene Interaction

Gene interactions in which an allele of one gene modifies or prevents expression of alleles of another gene is known as __________.

Numerous genes contribute to the wild-type red eye color in Drosophila. Two genes, brown and vermilion, produce eye pigments. What does the white gene do?

What are the two categories of gain-of-function mutations?

Two proteins interact to form a multimeric complex. When one of the proteins is mutated, there is a substantial loss of functional activity in the multimeric protein. This type of mutation is classified as __________.

Which mode of inheritance produces heterozygotes with phenotypes that differ from either homozygote but typically more closely resembles one homozygous phenotype than the other?

A mutation results in an enzyme that is partially active compared to the wild-type allele. This type of "leaky" mutation is classified as __________.

You cross a pure-breeding white flower with a pure-breeding red flower, and the offspring are all pink. This is an example of what type of inheritance?

What is the genotype for individuals with blood type O?

The amount of enzyme activity in a cell that is homozygous for a mutant allele is 400 units. The amount of enzyme activity in a cell homozygous for the WT allele is 200 units. The amount of enzyme activity in a heterozygote is 300 units. What type of allele is the mutant allele?

You discover a new allele of a gene important for tail formation in mice. WT mice have long tails, but mice heterozygous for the allele have short tails. When you cross two heterozygous mice together, you obtain a 2:1 ratio of short-tailed mice to long-tailed mice. None of the short-tailed progeny are homozygous. What type of allele results in short tails?

The amount of enzyme activity in a cell that is homozygous for a mutant allele is 400 units. The amount of enzyme activity in a cell homozygous for the WT allele is 200 units. The amount of enzyme activity in a heterozygote is 300 units. What is the dominance relationship between the WT and mutant allele for the phenotype of amount of enzyme per cell?

What are the three categories of loss-of-function mutations?

King George III of England and other members of the royal family were afflicted with a series of strange, seemingly unrelated symptoms including abdominal pain, rapid pulse, convulsions, and insanity. It has been determined that he likely suffered from porphyria, caused by a mutation in a single allele. What is the genetic term describing the alteration of multiple, distinct traits of an organism by a mutation in a single gene?

In yeast, there are three gene products required to synthesize the amino acid lysine. You cross two haploid lysine auxotrophs to form a diploid. The diploid fails to grow on plates lacking lysine. Which of the following can you conclude?

Individuals with blood type AB have which blood antibody(ies)?

Explain how the ch (Himalayan)allele and tyrosinase control the Siamese coat-color pattern. What is the underlying reason that certain parts of a Siamese cat (e.g., tail and ears)are darker than the cat's trunk?