BIO 202 HW 7

BIO 202 HW 7 - BIOL 202 HOMEWORK #7 Student's Name_Key_...

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BIOL 202 Student’s Name_____ Key____________________ HOMEWORK #7 Section number and TA’s name:_________________ DUE: March 27/28 in your discussion section. IMPORTANT: Please type (not hand-write) your answers onto the question sheet itself (this sheet). Please highlight or otherwise indicate the parts that you have typed with underlining or bold ing. 1. You are studying a strain of bacteria that has a mutation in one of the genes encoding proteins required for DNA replication. You isolate the following proteins from this strain of bacteria and test their function by allowing DNA replication in a test tube (in vitro) with the proteins isolated, Mg 2+ ions, a DNA template and free dNTPs: DNA polymerase III - the main polymerase in bacteria (elongates in DNA replication); has 3'->5' exonuclease proofreading ability DNA polymerase I - . Prokaryotic, implicated in DNA repair; has both 5'- >3'(Polymerase) activity and 5'->3' (Proofreading) exonuclease activity. DNA polymerase I removes the RNA primer from the lagging strand and fills in the necessary nucleotides of the Okazaki fragments in 5' -> 3' direction, proofreading for mistakes as it goes. It is a template-dependent enzyme, as it only adds nucleotides that correctly base pair with an existing DNA strand acting as a template Primase - is a form of RNA polymerase. In bacteria, primase binds to the DNA helicase forming a complex called the primosome. Primase is activated by DNA helicase where it then synthesizes a short RNA primer approximately 11 ±1 nucleotides long, to which new nucleotides can be added by DNA polymerase. No known DNA polymerases can initiate the synthesis of a DNA strand without initial RNA primers. Ligase
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This note was uploaded on 04/25/2008 for the course BIOL 202 taught by Professor Staff during the Spring '08 term at New Mexico.

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BIO 202 HW 7 - BIOL 202 HOMEWORK #7 Student's Name_Key_...

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