Problem set 3 key - Problem Set 3 Chapter 11 and part of 18 problems Questions 1 a Please describe the characteristics that all DNA polymerases

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Problem Set 3 Chapter 11 and part of 18 problems: Questions: 1. a) Please describe the characteristics that all DNA polymerases share. b) what is an important characteristic that most have but others lack? c) Please compare and contrast the overall structure and functions of DNA polymerase III and DNA polymerase I in prokaryotes. Be specific. a) all DNA polymerases, by definition, add nucleotides at the 3’ end of a growing chain of nucleotides. b) most DNA polymerases have the ability to proofread as they synthesize a new strand. This is a 3’ to 5’ exonuclease activity. c) Pol I consists of a single subunit, removes the RNA primers on the lagging strand with 5’ to 3’ exonuclease activity and fills in that area with DNA nucleotides. Pol III consists of ten subunits and synthesizes the leading strand and the Okazaki fragments of the lagging strand. 2. Please describe the role of DNA polymerase III in synthesis of the lagging strand. How is this different from synthesis of the leading strand? DNA synthesis on the lagging strand is away from the direction of the replication fork and is opposite to that of the leading strand. Synthesis on the lagging strand is discontinuous, while that of the leading strand is continuous. Short fragments (Okazaki fragments) of approximately one to two thousand bases are synthesized . On both strands however, DNA synthesis is in the 5’ to 3’ direction and is accomplished by adding new nucleotides to the 3’ end of the strand. 3.
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This note was uploaded on 04/27/2009 for the course BIO 340 taught by Professor Steele during the Spring '09 term at University of Arizona- Tucson.

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Problem set 3 key - Problem Set 3 Chapter 11 and part of 18 problems Questions 1 a Please describe the characteristics that all DNA polymerases

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