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Biology 202 Homework 4 Due: 10/2 or 10/3; in discussion Please type (not hand-write) ONLY the answers to question onto the question sheet itself (this sheet). Please highlight or otherwise indicate the parts that you have typed with italics , underlining or bold ing. If a question requires additional working, please include all of your work pages. Do not put the work on this answer sheet. 1. The drawing below depicts a replication fork undergoing replication of both the leading and lagging strand. (0.5 pts for each letter, total 2 pts) On the replication fork: a. Label all ends of template DNA and newly made DNA (in bold) with either 5’ or 3’. b. Identify the leading and lagging strands. c. Indicate the first Okazaki fragment made. d. Indicate the direction of synthesis (left to right or right to left) of each newly made DNA strand. The labels may be drawn in by hand and do not have to be typed.
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←answer 2. In the Meselson-Stahl experiment, 15N-labeled cells were shifted to 14N medium at what we can designate as generation 0. a. For the semiconservative model of replication, what proportion of 15N-15N, 15N-14N, and 14N-14N would you expect to find after 1, 2, and 3 replication cycles? (1.5 pts) Generation 15N-15N 15N-14N 14N-14N 1 0: (0%) 2: (100%) 0 (0%) 2 0: (0%) 2: (50%) 2 (50%) 3 0: (0%) 2: (25%) 6 (75%) b. Answer (a) in terms of the conservative model of replication. (1.5 pts) Generation 15N-15N 15N-14N 14N-14N 1 1: (50%) 0: (0%) 1 (50%) 2 1: (25%) 0: (0%) 3 (75%) 3 1: (12.5%) 0: (0%) 7 (87.5%) 3. Several different mutant strains of
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