Unformatted text preview: 3. RNA is removed and replaced by RNA polymerase I 4. helicase uncoils strands, primase puts down RNA primer, DNA polymerase III builds on chain on leading RNA strand (from 3’ of DNA on), builds Okazaki fragments on lagging strand (5’ on) Okazaki fragments: 1. RNA primase forms RNA primer 2. Primase released 3. DNA polymerase III synthesizes strand until it meets the previous one 4. DNA polymerase I replaces RNA primer 5. DNA ligase ‘stitches’ the pieces together DNA polymerase III has an error rate of about 1 in 10,000 base pairs Final error rate is ~ 1 in a billion Poly III can do approx 1000 bp/second in E. coli – slower in eukaryotes Rotates at about 3000 revolutions per minutes Telomeres Take a sequence like GGGATT – it’s repeated around 2500 times in humans Telomerase: preserves length of chromosomes on repeated sequences...
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- Spring '08