Question

Genetics 207 help! I did question #5 but I don’t think I did it correctly. I don’t understand how to do question #7

7. Imagine you had a large collection of Drosophila mutants and wanted to find mutants who were more tolerant to alcohol than WT flies. Design an experiment that would allow you to find these mutants. You can draw on the literature posted for Assignment 2 for ideas. (2)

Answer 1

5.- Remember what metaphase I is about: The homologous chromosomes align in the center to prepare to segragate in the next stage. Remember female flies DO recombine (this is for part b)), remember the positions of the black, vestigial and adh loci positions, and remember tha ploidy of flies so we can draw the correct number of chromosomes.

a) Vestigial wings black body and adh genes are all located in chromosome II (autosomal). This is our drawing:

Vestigial Black adh 0 Pair l Pair II Pair III Pair IV

b) Now we have to jump to the previous stage, in which crossing over occurs: Prophase. This would be a recombnination event that would recombine adh and vestigial:

Note that the branches were shifted.

7.- Alcohol tolerance is closely related to ADH, which is Alcohol DeHydrogenase. A higher activity of this enzyme produces higher levels of alcohol resistance. The experiment needs to be related to adh gene expression, and NOT to apply different levels of alcohol exposure, because the last one would lead to a big loss of flies. After finding a mutant with higher alcohol tolerance, finding a visible treat linked to adh (like black and vestigial) would lead us to identify alcohol tolerant offspring by the evident/visible treat.