Exams Fall 1999 7 03Exam 1 Name Section TA Exam starts at 11 05 and ends at 11 55 There are six pages including this cover page Please write your name on each page Please Look over the entire exam so you don t spend too much time on hard questions leaving easy questions unanswered Check your answers to make sure that they make sense To help us give partial credit show your work and state any assumptions that you make Question 1 Question 2 Question 3 30 points 40 points 30 points Name 1 A true breeding mouse strain exhibits two different rare traits When a male from the true breeding strain is crossed to a wild type female all of the female F1 progeny exhibit both traits whereas all of the male F1 progeny look wild type a 10 pts What is the mode of inheritance of the two traits b 10 pts The male and female F 1 mice described above are crossed to one another to produce F2 progeny Of the male F2 progeny 40 have both traits the rest of the F2 males either appear wild type or have only one trait or the other What fraction of the female F 2 progeny would you expect to have both traits v c 10 pts What is the map distance in cM between the genes for the two traits Name 2 a 6 pts You have isolated a yeast mutant that makes small colonies When you mate your haploid mutant to a haploid wild type strain the resulting diploids look like wild type What does this observation tell us about your mutant b 8 pts When the diploids from part a are sporuiated all of the tetrads appear to be PDs in the sense that they each have two small colonies and two normal sized colonies What does this observation tell us about your mutant c 6 pts You isolate a second mutant that also makes small colonies When a haploid of one small mutant is mated to a haploid of the other small mutant the resulting diploids appear normal What is the relationshipbetweenthe two small mutant strains Name d 10 pts When the diploids from part c are sporulated three types of tetrads are found Type I have 4 small colonies Type II have 1 normal and 3 small colonies Type III have 2 normal and 2 small colonies The cross produces 24 type I tetrads 24 type II tetrads and 2 type I11tetrads What is the map distance between the two mutations e 10 pts Give your best estimate for the number of tetrads out of 50 total described in part d that result from two crossovers in the interval between the two mutations Name 3 You have isolated a new mutationof phage X that makes plaques with rough edges You call the mutation rl Phage mutants in the repressor gene ci make clear plaques rather than the normal turbid plaques You cross a rl phage with a cl phage by coinfecting E coil with phage of both types One hundred plaques from the cross are examined and the following phenotypes and numbers are seen Plaque Phenotype rough turbid rough clear smooth turbid smooth clear Number 44 4 6 46 a 10 pts What is the distance between the rl and the cl mutations in map units Next you isolate a second mutationthat makes rough plaquesthat you call r2 When a rl cldouble mutant phage is crossed to a r2 mutant the following plaque types and numbers are seen Plaque Phenotype rough turbid rough clear smooth turbid smooth clear Number 491 499 9 1 b 10 pts What is the distance between the rl and r2 mutations in map units Name c 10 pts Draw a genetic map showing the relativeorder of the cl rl and r2 mutations as well as the distances that you have determined 7 03 Exam 1 Name oLUr 0 JS Section TA Exam starts at 11 05 and ends at 11 55 There are six pagesincludingthis cover page Please write your name on each page Please Look over the entire exam so you don t spend too much time on hard questions leaving easy questions unanswered Check your answers to make sure that they make sense To help us give partial credit show your work and state any assumptions that you make Question 1 Question 2 Question 3 30 points 40 points 30 points Name o L 0 1 A truebreedingmousestrainexhibitstwo differentraretraits Whena malefromthetrue breeding strain is crossed to a wild type female all of the female F 1 progeny exhibit both traits whereas all of the male F 1 progeny look wild type a 10pts Whatis the modeof inheritanceofthe twotraits 4 ExL o hL v td I o f h F ylo b 10 pts The maleand femaleF1 micedescribedabovearecrossedto one anotherto produce F2 progeny Of the maleF2 progeny 40 havebothtraits the restof the F2 maleseither appearwildtype or haveonlyonetrait or the other Whatfractionofthe femaleF2 progeny would you expect to have both traits F o t o tA K t 4 k 7 c 4 4 c 4 4 o I 10 1o 4 13 CP 4 4 4 c 10 pts What is the map distance in cM between the genes for the two traits i i OO C o LO I x lc o 1 2 0 1 4 o na v A X4 sb g b re s 4 0 Name 2 Sol h ov a 6 pts You have isolated a yeast mutant that makes small colonies When you mate your haploid mutant to a haploid wild type strain the resulting this observation tell us about your mutant k t4 diploids look like wild type What does 4 o F 4 4 v L Jf qL t v b 8 pts When the diploids from part a are sporulated all of the tetrads appear to be PDs in the sense that they each have two small colonies and two normal sized colonies What does this observation tell us about your mutant c 6 pts You isolate a second mutant that also makes small colonies When a haploid of one small mutant is mated to a haploid of the other small mutant the resulting diploids appear normal What is the relationship between the two small mutant strains Name S ov s d 10 pts When the diploids from part c are sporulated three types of tetrads are found Type I have 4 small colonies D Type II have 1 normal and 3 small colonies T Type I11have 2 normal and 2 small colonies N D 2 Z The cross produces 24 type I tetrads 24 type II tetrads and 2 type I11tetrads What is the map distance between the two mutations D Cs ce T C N Pb 2 7 2 o z x o 2 c 3 o r l1 e 10 pts Give your best estimate for the number of tetrads out of 50 total described in part d that result from two crossovers in the interval between the two mutations 2 4 ve t t Z 3 21 1 4 zt4 N1 D T …
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