MT2v1key - Bio 115 Winter 2011 Midterm#2 February 17 v1 Name Instructions Write your name at the top of every page Restrict your answers to the

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Bio 115, Winter 2011 Name__________________ Midterm #2, February 17 v1 _____________________________________________________________________________________________________________________________ _ page 1 page total: Instructions: Write your name at the top of every page. Restrict your answers to the space provided. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Answer the following questions with "true" or "false". (4 points each) For each "true" answer, give an example or explanation that supports the statement. For each "false" answer, explain why the statement is false. 1. Mediator complex specifies which genes will be activated for transcription by RNA Pol II. False. Transcriptional activators bind to their respective binding sites in promoters and specifyto which genes Mediator will be recruited, thus activating transcription. In other words, Mediator will indiscriminately bind any activators present in the nucleus. 2. ATP hydrolysis is not required for splicing chemistry, but is required for spliceosome function. True. The two chemical steps of splicing involve making and breaking the same kind of bonds, which is energy neutral. However, the spliceosome must rearrange several RNA:RNA and RNA:protein interactions to identify and position the intron for splicing. 3 . Expression of a transcriptional activator always results in activation of its target genes. False. In addition to the presence of the activator, it must be in the right place and in an active conformation, which usually depends on a cellular signal. Furthermore, the chromatin of the target genes must be accessible for transcription. 4. An important feature of many DNA recognition domains is their ability to dimerize. True. Dimerization increases both binding sequence specificity and sensitivity such that small changes in the protein concentration can effect a large change in transcription levels. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Short answer. Limit your answer to the space provided. (4 points each) 5. Which technique would you use to determine whether the transcriptional activator PHO4 binds to the PHO5 gene promoter when yeast are grown in low phosphate buffer? What are the specific reagents you need for the experiment? Chromatin IP. I would need an antibody against PHO4 (coupled to beads), crosslinked and sheared yeast chromatin from yeast grown in low phosphate buffer (and high phophosphate buffer for comparison), and PCR primers directed to the PHO5 promoter. 6. What mechanism ensures that only RNA Pol II transcripts are capped? Capping enzymes are specifically recruited to the hyperphosphorylated CTD of Pol II and cap the
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MT2v1key - Bio 115 Winter 2011 Midterm#2 February 17 v1 Name Instructions Write your name at the top of every page Restrict your answers to the

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