DAKL7-032410DNARepair

DAKL7-032410DNARepair - DNA Repair Image...

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Unformatted text preview: DNA Repair Image: http://www.wsu.edu/~smerdon/ “Our current understanding is that DNA is the only molecule that organisms repair rather than replace.” – your book, pg.531 Review of Last Lecture: Mutagenesis • Mutations are the source of genetic diversity, but usually have a negative impact on gene function. • Mutations can arise spontaneously , or by exposure to a mutagen • Point mutations can be caused by rare nucleotide tautomers, direct damage to bases (cytosine deamination, oxidation, or an abasic site), or by insertion of a base analog. • Insertions and Deletions can be caused by Intercalating Agents • Many human diseases are caused by triplet repeat expansions . These can be caused by strand slippage during replication. • Exposure to UV light can cause covalent linkages between adjacent T nucleotides on the same strand (Thymidine dimers) Learning Objectives for DNA Repair Mechanisms I. Direct repair I. Pre-replication mechanisms • Nucleotide Excision Repair • Bypass polymerase • Base Excision Repair III. Post-replication mechanisms • Cell-cycle checkpoints and apoptosis • Mismatch repair • Double-strand break repair IV. DSB repair in non-dividing cells Pre-replication vs Post-replication repair: Mutations are NOT “fixed” (permanent) until replication DNA Repair Mechanisms I. Direct repair I. Pre-replication mechanisms • Nucleotide Excision Repair • Bypass polymerase • Base Excision Repair III. Post-replication mechanisms • Cell-cycle checkpoints and apoptosis • Mismatch repair • Double-strand break repair IV. DSB repair in non-dividing cells Direct repair: Photolyase uses light energy to repair UV damage Fig 15-22 Photolyase binds to the photodimer and splits it to regenerate the original bases = Direct reversal of damaged DNA DNA Repair Mechanisms I. Direct repair I. Pre-replication mechanisms • Nucleotide Excision Repair • Bypass polymerase • Base Excision Repair III. Post-replication mechanisms • Cell-cycle checkpoints and apoptosis • Mismatch repair • Double-strand break repair IV. DSB repair in non-dividing cells-...
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This note was uploaded on 04/25/2010 for the course BIOL 202 taught by Professor Kieber-hogan during the Spring '08 term at UNC.

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DAKL7-032410DNARepair - DNA Repair Image...

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