NAME STUDENT ID MCB 140 FINAL EXAM Spring 2007 NAME Please print STUDENT ID REMINDERS You have 180 minutes for the 225 point exam Print your name and ID on each page of the exam You will lose points if you forget to do this There are 17 pages total including this cover page The last two pages are work space no problems All pages must be turned in Only the front of each page will be graded If you use the back of a page transcribe your answer to the front of the page Use a non programmable calculator Do not write below this line 1 25 10 15 2 11 11 10 3 2 12 10 4 2 13 15 5 7 14 20 6 3 15 10 7 35 16 5 8 10 17 10 9 15 18 20 TOTAL 225 Page 1 of 17 NAME STUDENT ID Questions on Prof Urnov s section 1 The following is Fig 5 13 from your textbook It shows one of the most majestic achievements of the scientific method a map of the Drosophila genome obtained without any knowledge of the chemical basis of heredity i e solely via genetic analysis NAME STUDENT ID a 5 pts We talked about the fact that unlinked genes recombine at a frequency of 50 That said for some reason the genetic distance on Chr 1 between two linked genes aristaless antenna and blistered wings is a whopping 107 map units How could this impossible value have been experimentally measured Did they observe recombination 107 of the time b 20 pts A white eyed male with normal veins on its wings and a body of wild type color is mated to a red eyed female with thick veined wings and a black body All the progeny of this cross are wild type Female progeny of this cross are mated to white eyed males with thick veins on their wings and a black body One thousand progeny from this cross are phenotyped Write out the phenotypic classes observed in this progeny and the number of flies in each class assuming perfect compliance with the genetic distances shown above and perfect compliance with Mendel s laws NAME STUDENT ID Questions on Prof Cline s section For each question below 2 6 BRIEFLY EXPLAIN your answer even if your answer is there is no logical basis from Genetic principles and or vocabulary for an answer other than can t say based on the information provided Remember not to overthink the questions 2 Consider two different dominant gain of function alleles of the same gene in the German Shepherd dog QA is an antimorph while QH is a hypermorph The phenotype of the null Q allele is no tail and the mutant allele is fully recessive a 2 pts What can you say about the likely phenotype of a QA German Shepherd b 2 pts Would you expect the mutant phenotype of QA dogs to be qualitatively similar to that of QH dogs or instead be qualitatively different c 2 pts QA QH dogs are wildtype Would it be correct therefore to say that the two gain of function alleles complement d 3 pts If we reverted the dominance of QA and QH generating QA and QH respectively what would the likely phenotype be of a QA QH dog e 2 pts In light of the information given you in part c above what if anything could you predict about the phenotype of a QA H Q dog if you were told that QA and QH satisfy expectations for a cis trans test for allelism Assume that QA H is a doubly mutant allele created by recombination between QA and QH not very likely of course NAME STUDENT ID 3 2 pts The mutagen ethylmethane sulfonate will generate null alleles but it is particularly effective at generating a wide spectrum of hypomorphic point mutants as well Brenner and crowd used proflavin as the mutagen for the rII gene of phage T4 in their famous experiments exploring the nature of the genetic code They demonstrated that the genetic code was commaless in part by showing that certain of their point mutant alleles could be suppressed by certain other of their point mutant alleles Do you think that some of the mutations they induced in rII by proflavin would likely be suppressed by some of the mutations that one might typically induce in rII by ethylmethane sulfonate 4 2 pts To move DNA around fly workers generally use an engineered immobile genetic source of P element transposase called delta 2 3 derived from DNA that was originally introduced into an M strain animal After many generations will female flies from the delta2 3 strain eventually come to behave like P strain females and generate eggs with a P cytotype 5 The mechanism of sex determination can be remarkably messy in some species with different races of the same species having different GSD systems operating Consider such a species in which race Q has a ZZ ZW system of the active W type while race R of the same species but geographically isolated from the other has an XX XY system of the active Y type The Z and X chromosomes of the two races are essentially identical genetically and this sex chromosome carries 10 of all the genes In contrast the W and Y chromosomes carry very few genes a 2 pts Which if either of the two races is are likely to need a sex chromosome dosage compensation system b 2 pts Which if either of these species is likely to use a sexchromosome autosome balance system of sex determination NAME STUDENT ID c 3 pts If you crossed a Q strain male with an R strain female what would you expect the sexual phenotype s of the offspring to be 6 3 pts Given the following genotype of fruit fly FRT a b c d e a b c d e FRT where a through e are recessive cell autonomous mutant alleles that can generate distinguishable clone phenotypes on the thorax back of the adult If a brief pulse of Flippase were introduced during the development of this fly to induce a single clone of phenotypically e mutant tissue on the adult thorax without respect to what other mutant phenotypes that e clone might exhibit what would you expect the phenotype to be of the twin spot partner of that e clone with respect to these five genes no explanation needed Questions on Prof Brem s section 7 35 pts Imagine that you are studying genetic differences between the Junglefowl and Leghorn varieties of chicken whose pictures we saw in class You mate the parents to generate F1 s and then cross the F1 s among themselves to get 100 F2 birds You first get interested in the quantitative trait of egg weight By linkage analysis you map a very strong locus that appears to explain essentially all the genetic variation in egg weight in the cross The LOD score is highly significant and you are convinced that the trait is Mendelian controlled by the single locus you …
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