BIOL 2300 Exam 2: Quiz Questions

BIOL 2300 Exam 2: Quiz Questions How do we know that specific genes are linked on a single chromosome, in contrast to being located on separate chromosomes? - ANSWER-*the genes segregate together during gamete formation* Imagine that you have joined a genetics lab on campus and want to gain experience mapping genes in Drosophila. You conduct a series of two-point mapping crosses involving five genes located on chromosome III and obtain the following percentage of recombinant offspring: h-cu: 23.5% eyg-h: 9.0% eyg-cu: 14.5% rai-eyg: 18.5% rai-h: 9.5% rai-cu: 33.0% th-cu: 6.8% th-h: 16.7% th-eyg: 7.7% th-rai: 26.2% Considering that rai is near the end of chromosome III, construct a map of these genes. For (a), (b), (c), and (d), enter the correctly named gene, for example, if you think, eyg goes in blank "d", then enter eyg. Order your genes by their distance to rai, with the gene closest to rai going in blank a and the gene most distant going in blank d. For blanks 1, 2, 3, and 4, enter the map distances for the respective genes. For example, the distance in blank 1 would be the distance between rai and the gene you entered in bla - ANSWER-a) *h* b) *eyg* c) *th* d) *cu* 1) *9.5* 2) *9.0* 3) *7.7* 4) *6.8* The genes for mahogany eyes and ebony body are approximately 25 map units apart on chromosome 3 in Drosophila. Assume that a mahogany-eyed gray bodied female was mated to an red eyed ebony-bodied male and that the resulting F 1 phenotypically wild-type (red eyed, gray bodied) females were mated to mahogany, ebony males to obtain an F 2 generation. Which of the following phenotypes would be expected in the F 2 offspring? Hint: Really pay attention to what the question is asking you to cross - approach this in a step-wise fashion and you should be fine......... - ANSWER-*red eyed, gray bodied* *mahogeny eyed, gray bodied* *red eyed, ebony bodied* *mahogeny eyed, ebony bodied*