biog 104 lab quiz 2 answers

biog 104 lab quiz 2 answers - Green → white> yellow →...

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BioG 104 Pre-lab quiz 2 Answers 1. Draw a double-chromatid chromosome and mark the loci of two linked genes, red and blue. (1) Blue gene and red gene should be on different chromatids 2. If two genes are linked, then you should see more parental than non-parental ditypes after meiosis. Express this in terms of null and alternative hypotheses. (2) H 0 : There are equal numbers of parental and non-parental ditypes after meiosis H a : The numbers of parental and non-parental ditypes after meiosis are not equal 3a. Give one reason why a cross-over might not be detectable, and briefly explain why. (2) Cross-over between sister chromatids 3b. If there are more cross-overs than detected, what would this mean about an estimate of map units? (1) Underestimate: focal gene is further from the centromere (more map units) than you estimated. 4. Consider the following biochemical pathway for pigment production in a bacterium:
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Unformatted text preview: Green → white --> yellow → pink a. What colour is the prototroph strain? (1) White b. Choose one step of the pathway to be mutated (cross out the appropriate arrow). What colour is the auxotroph created by this mutation? (1) Auxotroph will be the colour before the arrow you crossed out, e.g. if you crossed out the second arrow, it will be yellow. c. In a syntrophic feeding experiment, which strain(s) (if any) would you need to feed your mutant to make the end product? (1) Any colour after your auxotroph, except for pink, since this is the prototroph and doesn’t make excess product. d. You are given a brown auxotroph that feeds mutually with the yellow strain. Add the appropriate extra step to the pathway to include the brown intermediate. (1) Branched pathway: Green → brown → white… (parallel to branch with yellow)...
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