Dis.Ques.4%20-%20KEY - Genetics - BIO325 Discussion...

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Genetics - BIO325 Discussion questions 4 1. What are the three enzyme activities present in E. coli DNA polymerase I? 1. 5' to 3' polymerasing activity – filling in gap left by RNA primer 2. 3' to 5' exonuclease activity - proofreading 3. 5' to 3' exonuclease activity – removing the RNA primer 2. During DNA replication in E. coli , DNA was isolated at different intervals. DNA isolated at the beginning included single-stranded fragments of about 1000 nucleotides long. When DNA replication was allowed to proceed for a longer period of time, lower frequency of short fragments and many more long fragments were obtained. (a) What do the short single stranded DNA fragments correspond to (lagging strand fragments or leading strand fragment)? Lagging strand fragments (b) What is the name given to these short single stranded fragments? Okazaki fragments (c) Why are long fragments observed after longer periods of synthesis? Because some of the early polymerised Okazaki fragments have already been ligated.
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This note was uploaded on 12/17/2009 for the course BIO Genetics taught by Professor Saxena during the Spring '08 term at University of Texas at Austin.

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Dis.Ques.4%20-%20KEY - Genetics - BIO325 Discussion...

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