midter2 - CHEM114C Midterm II Name ID Please write your...

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CHEM114C Name ______________________________ Midterm II -1- May 20, 2008 ID#________________________________ Please write your name on each page. Your exam should have 5 pages including this cover page, with a total of 4 questions. Be certain that all work you want graded is written in permanent ink. You can use the back of the page to continue your answer. Do not use a calculator. This exam is 60 min long – work swiftly, most answers are short. GOOD LUCK! Your score 1. (30)_________ 2. (30)_________ 3. (30)_________ 4. (30)_________ Total (120)______________ This midterm counts 25% towards your final grade in this course. If you missed Midterm I, it counts for 33.3%.
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CHEM114C Name ______________________________ Midterm II -2- 1. Transcription is carried out by RNA polymerases. (30 total) 1.a) What is the subunit structure of the elongating E.coli RNA polymerase and which ion is located in the active site? (4) α 2ßß’ Mg2+ is located at active site 1.b) Write down the reaction that is catalyzed by this enzyme. (4) as on p.920 or Fig.25.6 1.c) Diagram (on backpage) the transcription bubble indicating the directionality of sense and anti-sense DNA strands and the nascent RNA. (4) as in Fig.25.3 or 25.7 1.d) What are the two footprinting techniques that reveal how the RNA polymerase interacts with the template? What do they tell us, and how do they work? (Use the backpage) (6) Dnase1 and DMS footprinting Dnase 1 foot printing reveals where the protein (RNApol) is bound, because the Dnase 1, which is a nuclease enzyme, does not have access to the DNA where the protein in bound DMS foot printing reveals also where protein is bound (but closer contact is required for protection). In addition, DMS reveals where the DNA helix is distorted or single stranded (in the bubble), as the guanines are more prone to methylation. DMS fottprinting works by methylating guanines. Then methylated guanines are cleaved with piperidine. (Diagram is optional, not required.
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This note was uploaded on 10/30/2010 for the course CHEM 114C taught by Professor Alexanderhoffmann during the Spring '08 term at UCSD.

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midter2 - CHEM114C Midterm II Name ID Please write your...

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