Exam II-09

Exam II-09 - Page 1 Bio 3324 Molecular Biology Exam II...

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Page 1 Bio 3324 Molecular Biology Exam II November 19, 2009 This exam is worth a total of 100 points 1. a. The abundance of various proteins varies enormously within a cell. Give three levels of regulation that may account for this variance. (3 pts.) b. Given that prokaryotic genomes are double stranded DNA and mRNA is single stranded, are all mRNAs transcribed from the same DNA strand? (2 pts.) c. What information does RNA polymerase use to select the template strand? (3 pts.) d. How does E. coli RNA polymerase recognize specific promoter sequences at initiation but then continue to transcribe all other sequences efficiently? (4 pts.) e. Prokaryotic organisms and their viruses use two different mechanisms to rapidly alter which genes are being transcribed. Discuss the mechanism i) that bacteria use to activate sporulation specific genes (2 pts.) ii) that lambda virus uses to switch from transcription of early to late genes. (2 pts.) 2. a. In prokaryotes, the promoter is defined as the region of DNA contacted by RNA polymerase. Why is this definition not appropriate for eukaryotic promoters? (3 pts.) b. Of the following promoter elements: i) basal promoter (includes TATA box) ii) activating sequences within 200 bp of the start point iii) enhancers which can function both upstream or downstream of the start point of transcription? Which can function in either orientation compared to the start point of transcription? (4 pts.) c. Eukaryotes use three different RNA polymerases to transcribe different sets of promoters. For RNA polymerases I, II and III, which types of genes are transcribed by each? (3 pts.) d. Each of the RNA polymerases has an initiation factor that includes TBP (the TATA binding protein). What is the role of TBP? (3 pts.)
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Page 2 3. a. In both bacteria and eukaryotes, the template strand of transcribed genes is preferentially repaired after DNA damage. Explain the connection between
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Exam II-09 - Page 1 Bio 3324 Molecular Biology Exam II...

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