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Unformatted text preview: 1 Biology 41 FINAL Fall 2006-07 December 14, 2006. ANSWER SHEET Question 1. (12 points) In an attempt to cure baldness, you are studying genes that affect the coats of mice. If you look at the cells in the skin of a wild-type mouse, you see that some cells produce hairs and some cells do not. You have identified four pure-breeding lines that contain single mutations that affect how many hairs are formed. Three of your mutants ( kingkong, werewolf and sasquatch ) cause each skin cell to form a hair, whereas in the fourth mutant ( mrclean ) none of the cells form hairs. When you cross each mutant to wild type, the F1s are kingkong X WT = WT werewolf X WT= WT sasquatch X WT= all cells form hairs mrclean X WT= WT i. (6 points) You want to know whether these mutants affect the same gene, but you are also impatient and want to know the answer in one generation. The following chart lists several crosses between homozygous mutants. For each, indicate whether the cross can be used to UNAMBIGUOUSLY determine whether two mutations are in the same gene by circling the choice. Briefly explain in the box provided. cross Results are Briefly explain your choice (10 words or less) kingkong x werewolf Ambiguous Unambiguous 2 recessive mutations, if F1 is WT they are not allelic kingkong x mrclean Ambiguous Unambiguous 2 recessives, but phenotypes opposite, so hard to predict the phenotype of kk/mc if they were allelic sasquatch x werewolf Ambiguous Unambiguous Sasquatch is dominant sasquatch x mrclean Ambiguous Unambiguous Sasquatch is dominant Point allocation: i) was 0.5pt for each Ambigous/Unambigous choice, and 1 pt for each explanation. ii. (2 points) What is the name of this type of genetic test? complementation test You find that werewolf mice are deficient only in enzyme W and mrclean are deficient only in enzyme M. You can purify these enzymes and make a solution that can be applied to the heads of mice (and someday to humans). iii. (2 points) If you want to grow hair, which enzyme would you choose to apply? (circle one) M W iv. (2 points) Explain in 1-2 sentences why you chose that enzyme. 2 Assuming that the recessive mutations are a loss of gene function, and that without MRCLEAN, no hairs grow, the normal function of MRCLEAN must be to produce a product to grow hair Question 2. (12 points) In the Arabidopsis plant, glabrous vs. hairy, serrated vs. smooth and pale vs. dark green are each determined by a single pair of alleles. A plant heterozygous for all three genes is crossed to a glabrous, smooth, pale plant to produce the following offspring: hairy, pale, serrated 100 hairy, pale, smooth 20 hairy, dark, serrated 100 hairy, dark, smooth 20 glabrous, dark, serrated 20 glabrous, dark, smooth 100 glabrous, pale, serrated 20 glabrous, pale, smooth 100 i. (5 points) Construct as complete a map, including distances and gene order (if possible) from this data. Be sure to note any ambiguities in the relative map positions of the three genes. any ambiguities in the relative map positions of the three genes....
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This note was uploaded on 06/25/2008 for the course BIOSCI 41 taught by Professor Simoni,r;bergmann,d during the Fall '07 term at Stanford.
- Fall '07