04_2nd_midterm_Key_Sp0

04_2nd_midterm_Key_Sp0 - Name:_Key_ ID#:_Section:_ 2nd...

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Name:_____________ Key ________________________ ID#:___________________________________________Section:________ 2 nd Midterm LS4 March 3, 2004 1. (8 pts) 2. (6 pts) 3. (10 pts) 4. (12 pts) 5. (10 pts) 6. (8 pts) 7. (14 pts) 8. (14 pts) 9. (8 pts) 10. (10 pts) SHOW WORK FOR PARTIAL CREDIT 1. (8 pts) some adenine auxotrophs in bakers yeast have red colonies instead of the usual white color (they require low levels of adenine to grow). Ade1 is such a strain. Additional Ade auxotrophic strains 2, 3 &4 grow into white colonies on low levels of adenine. Supplementation tests show these results: Substance added to medium Mutant strain W X Y Z Ade 1 ----r e d 2- ++++ 3- + --+ 4- + - ++ a. draw the pathway leading to Ade and indicate where each mutant is blocked. (start) W 2 Y 4 Z 3 X 1 ADE b. What is the origin of the red color? i. excess X through failure to convert to Ade ii. excess X through failure to convert to Y iii. excess Y through failure to convert to Z iv. excess Z through failure to convert to Ade v. excess Z through failure to convert to X
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2. (6 pts) 6 bacterial strains were tested for their ability to produce recombinants through conjugation in pairs, with these results (- = no recombinants, + = few recombinants and m = many recombinants). Strain number Strain number 1 2 3 4- + - 5+ - m 6- m - a. which strains are Hfr? i) 1 & 6 ii) 2 & 3 iii) 3 & 4 iv) 3 & 6 v) 5 & 6 b. strains 1, 2 & 3 are auxotrophic for lys while strains 4, 5 & 6 are prototrophic. Indicate which strain you would pick for use as a potential recipient to map the lys gene. #2 3. (10 pts) Two Hfr strains, A and B, show the transfer of markers a, b, c, d & e in the following numbers (from 1000 colonies on a master plate following uninterrupted mating).
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04_2nd_midterm_Key_Sp0 - Name:_Key_ ID#:_Section:_ 2nd...

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