Exam1_2008_key - Name_ UA Net ID _ EXAM I BIOCHEMISTRY 466...

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Name____________________________ UA Net ID _____________ EXAM I BIOCHEMISTRY 466 - SPRING 2008 Instructions: 1. Write your name and UANetID code on ALL pages. Pages may be separated during grading. 2. This Exam has 6 questions on 6 pages after the cover sheet and a total of 150 POINTS. 3. Show your work on mathematical problems, including units. 4. Answer briefly in the space provided. Filling all available space is not necessary. Scoring on Individual Questions: 1. ________ (25 points) 2. ________ (25 points) 3. ________ (25 points) 4. ________ (25 points) 5. ________ (24 points) 6. ________ (26 points) Total ________ (150 points)
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Name____________________________ UA Net ID _____________ 1 1. (25 points) DNA and DNA topology a. (4 points) Approximately 30% of human DNA describes protein coding regions, but only about 1.5% of human DNA becomes messenger RNA. What is the explanation for this difference? Protein coding exons are interrupted by introns. Other non-coding segments are also present, including 5’ and 3’ UTRs and regulatory sequences b. (6 points) The E. coli genome is a circular DNA of length 4.6 x 10 6 bp. What are the approximate length and molecular weight of this DNA? To approximate, use the relationship that 1 um = 2 mD = 3 kbp Length = ( 4.6 x 10 6 bp ) / (3000 bp/ micrometer) = 1.5 x 10 3 um MW = (1.5 x 10 3 um ) (2 x 10 6 mD / um ) = 3 x 10 9 c. (6 points) What is the linking number of relaxed, circular E. coli DNA? L k = ( 4.6 x 10 6 bp ) / (10.5 bp / turn ) = 4.4 x 10 5 d. (9 points) What are three differences between the enzymatic reactions of Type 1 and Type II DNA topoisomerases? Type 1: Change linking number by 1 per reaction; only act on left handed supercoils; no ATP requirement Type 2: Change linking number by 2 per reaction; act on left or right handed supercoils; ATP is required requirement
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Name____________________________ UA Net ID _____________ 2 2. (25 points) Briefly describe the structure of chromatin and chromosomes based on structural and biochemical studies. Include mention of specific proteins at different levels of chromosome
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This test prep was uploaded on 04/02/2008 for the course BIOC 466 taught by Professor Hallick,dieckmann,horton during the Spring '08 term at University of Arizona- Tucson.

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Exam1_2008_key - Name_ UA Net ID _ EXAM I BIOCHEMISTRY 466...

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