Flies with a dominant mutation in a particular gene have an additional set of wings. Through mapping techniques, you identify a candidate gene, gene X, on an autosomal chromosome that you think results in extra wings when mutated. When you sequence gene X in the mutant fly with extra wings, you notice a missense mutation in the middle of the coding region of gene X. What is the best way to verify that the mutation in gene X is responsible for the dominant phenotype?
a. Starting with a wild-type fly, knockout gene X to generate a null allele and see if flies that are heterozygous or homozygous for the null allele have extra wings.
b. Starting with the mutant fly that is heterozygous for the dominant allele, insert a wild type copy of gene X (complete with its own promoter) elsewhere in the genome of the fly and see if it rescues the mutant and results in normal/wild-type wings.
c. Starting with a mutant fly that is heterozygous for the dominant allele, replace the dominant mutant allele with a wild type version of the gene via homologous recombination and see whether flies with the replacement have normal/wild type wings.
d. Starting with a homozygous wild-type fly, replace one copy of wild-type gene X with a version carrying the dominant mutation via homologous recombination, and see whether flies with the replacement have extra wings.
e. either C or D
You have a strain of flies that are homozygous for a deletion of 2 neighboring genes, A and B (genotype aabb). Wild type flies have transparent wings but these aabb flies have rainbow-colored wings. Which of the following experiments would provide you with more information about which of these genes (if either) is responsible for the rainbow-colored wings?
a. Starting with a wild-type fly, create a transgenic fly that is homozygous for deletion in both genes A and B and see if you get the rainbow-colored wings.
b. Delete gene A alone and gene B alone in 2 independent wild-type flies and see whether flies homozygous for either deletion have rainbow-colored wings.
c. Starting with a mutant fly with rainbow-colored wings, introduce both wildtype genes A and B into a new place in the genome of the fly and see if normal wing color is restored.
d. non of the above
