36_printout - Lecture 36: DNA replica2on Lecture 36...

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Unformatted text preview: Lecture 36: DNA replica2on Lecture 36 (4/5/11) DNA replica2on Reading assignment: pp. 975 ­91. Problems: N&C ch. 25, #1 ­2, 5, 7 ­9. SG p. 317, #1 (do not worry about Tus or Dam methylase yet),#2. 1 Lecture 36: DNA replica2on The Kornberg enzyme DNA Pol 1 2 Lecture 36: DNA replica2on Polymeriza/on is a thermodynamically favorable reac/on (dNMP)n + dNTP (dNMP)n+1 + PPi PPi 2Pi phosphatase irreversible reversible Net ΔG=0 ΔG =  ­7kCal/mol Accuracy is about 1 mistake in every 104 ­105 bp 3 Lecture 36: DNA replica2on 3’ ­5’ exonuclease ac/vity (proof reading func/on) Proof reading improves accuracy by 102 ­103 fold. Repair mechanisms improves accuracy by another 102 ­103 fold. Gene2c analysis shows that the overall error rate for the replica2on of gene2c informa2on is 1/109 ­1/1010 bp. 5’ ­3’ exonuclease ac/vity 4 Lecture 36: DNA replica2on A Pol I mutant with only 1% of the 5’ ­3’ polymerase ac/vity is viable. “Is Pol I “the” replica/on enzyme ?”  ­ asked John Cairns Search for the real polymerase ! Tom Kornberg Pol 2 Pol 3 5 Lecture 36: DNA replica2on - A dimer 6 Lecture 36: DNA replica2on 7 ...
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This note was uploaded on 04/08/2011 for the course BIO BM 3350 taught by Professor Blakenship during the Spring '11 term at Cornell University (Engineering School).

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