Note: You can assume that
expressing the qtg gene from one of the two chromosomes is
sufficient for its wild-type function. If it helps, you can further
assume that the two mutations in part (c) do not occur on the same
chromosome.
Question 3. (7 points) Recessive mutations mapping near a gene in Drosophila melanogaster called question-three-gene (qtg) show two very different phenotypes in homozygous flies. One class of mutants experience early embryonic death (qtgE), while the other class of mutants survives to adulthood, but exhibits abnormal wing morphology (qtgW). You clone and sequence the mutant alleles from these flies. The figure below indicates the locations of the mutations and the resulting phenotype (E or W) for each mutation. The mutations causing the E phenotype map to three different locations. The arrow represents the gene’s transcription start site and the direction of transcription. Each number below a mutation gives its location relative to the transcription start site (in nucleotides). Using this information, answer these questions: E3 Premature STOP codon E1 E2 1540 -3120 -10 +1 +19 (not to scale) a. What is the null phenotype of the qtg gene? Explain your answer. (Hint: Think about concepts from Chapter 16.) b. Why might the qtgWmutation give a different phenotype from the E mutants? Explain your answer. c. What phenotype do you predict for a fly with the following genotypes: Heterozygous for qtgW and qtgE2 Heterozygous for qtgW and gtgE1