The vestigial gene in fruit flies can have a mutation, vg-, which confers tiny, useless wings; this phenotype is recessive to wild-type (normal size) wings. The vestigial gene is on chromosome 2. The wild-type is vg+.
The gene, hairy, in fruit flies can have a mutation, h-, that confers a hairy body; this phenotype is recessive to a wild-type, non-hairy body. The hairy gene is on chromosome 3. The wild-type is h+.
In fruit flies, the sex chromosome is chromosome 4.
1. In fruit flies, a gene, nowings, has a recessive mutant allele (nw-) that causes flies to have no wings.
a. What is the wing phenotype of a fly with the following genotype: vg+vg- nw- nw-?
b. What is the term for two genes that interact to influence a phenotype?
c. A researcher develops a true-breeding line of flies with wings that are vestigial. If this fly with vestigial wings is crossed with a fly that is homozygous for the nowings mutation, what percentage of their offspring will have wings? Please describe your reasoning and/or draw a Punnett Square. Hint: you only need to know part of the genotype of the fly with no wings to answer this question.
2. In mealworms, gene A has two alleles A1 and A2. In true-breeding lines with the A1 allele, the larvae are white. In true-breeding lines with the A2 allele, the larvae are orange. How could you determine whether one of these alleles is dominant or whether the alleles show incomplete dominance? Show the relevant cross and explain.