30_DNA_Repair (3)

30_DNA_Repair (3) - DNA Repair Image:...

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DNA Repair Image: http://www.wsu.edu/~smerdon/
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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)
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DNA Repair Mechanisms I. Direct repair I. Pre-replication mechanisms Nucleotide Excision Repair Bypass polymerase Base Excision Repair Cell-cycle checkpoints and apoptosis III. Post-replication mechanisms Mismatch repair Double-strand break repair IV. DSB repair in non-dividing cells
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Pre-replication vs Post-replication repair: Mutations are NOT “fixed” until replication
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DNA Repair Mechanisms I. Direct repair I. Pre-replication mechanisms Nucleotide Excision Repair Bypass polymerase Base Excision Repair Cell-cycle checkpoints and apoptosis III. Post-replication mechanisms Mismatch repair Double-strand break repair IV. DSB repair in non-dividing cells
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Direct repair: Photolyase uses light energy to repair UV damage Fig 15-22
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DNA Repair Mechanisms I. Direct repair I. Pre-replication mechanisms Nucleotide Excision Repair Bypass polymerase Base Excision Repair Cell-cycle checkpoints and apoptosis III. Post-replication mechanisms Mismatch repair Double-strand break repair IV. DSB repair in non-dividing cells
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  recognize damage   unwind to make bubble   nick 5’ and 3’ remove damaged fragment
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This note was uploaded on 06/27/2011 for the course BIOL 202 taught by Professor Kieber-hogan during the Spring '08 term at UNC.

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30_DNA_Repair (3) - DNA Repair Image:...

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