Gen371 Sample Midterm Answer Key

Gen371 Sample Midterm Answer Key - Gen371 Sample Midterm...

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1/26/11 4:19 PM Gen371 Sample Midterm Answer Key Page 1 of 8 http://courses.washington.edu/au371mkr/resources/problems/sample_midterm-key.html Sample midterm -- answers 1. The Agouti protein is normally made only during a brief period during hair growth. The diagram below represents a transcription bubble in the Agouti gene. The asterisk marks the approximate location of a mutation that causes excessive transcription of the Agouti gene. (a) (i) Give a hypothesis for how the mutation causes excessive transcription: A mutation in the regulatory (promoter) region causing deregulated transcription (ii) On the transcription bubble diagram, draw RNA polymerase and an RNA transcript consistent with your hypothesis. Mark the 5' and 3' ends of the RNA and mark the template and coding strands. (b) A different mutation in the Agouti gene also causes excess Agouti protein to accumulate but the transcription rate and the protein itself in this mutant appear to be completely normal. Suggest an explanation for this phenotype. Several possible explanations… for example, it could be a mutation in the untranslated regions of the mRNA that slows the rate of mRNA degradation, leading to accumulation of mRNA and therefore higher concentrations of Agouti protein. Or, it could be a silent mutation that exchanges a rare codon for a frequent codon, increasing the rate of translation. [Since the protein itself is unchanged, it cannot be an amino acid change that reduces the rate of Agouti protein degradation.] (c) A 6-frame translation map of the Agouti region is shown (the Agouti gene does NOT extend beyond this map): Genomic chromosomal DNA was denatured and then hybridized with mature, wild type Agouti mRNA. An electron micrograph representation (below) shows the RNA-DNA hybrid that was formed (thick portion=RNA-DNA hybrid; thin portion = DNA). Based on this EM, box the portion of the ORF map above that corresponds to the Agouti gene. What led you to your conclusion? The looped-out portion on the EM must Home Course mechanics Help hours Calendar Syllabus Lectures, Podcasts Quiz Sections Practice problems Exams GoPost Send email to class Useful links The Gradiator
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1/26/11 4:19 PM Gen371 Sample Midterm Answer Key Page 2 of 8 http://courses.washington.edu/au371mkr/resources/problems/sample_midterm-key.html represent an intron that was spliced out of the primary (pre-mRNA) transcript. .. it forms a loop because on the mRNA there is no corresponding sequence. Therefore, on the ORF map, we have to look for two ORFs that are on the same strand (even if not in the same reading frame). 2. Teletubbies are strange creatures that appear on kids’ TV shows. A well-known TV network is trying to decipher Teletubby genetics by doing a transposon mutagenesis of Teletubbies. Here is some of what is known so far: Teletubbies are diploid with 3 chromosome pairs Males are XY and females are XX There is no crossing over in male meiosis but there is normal crossing over in females Moreover, the following markers are known:
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Gen371 Sample Midterm Answer Key - Gen371 Sample Midterm...

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