DNA Damage and Repair

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DNA Damage and Repair

• ??? ??? 906113

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??

• ??
• DNA damage???
• DNA repair???
• ??
• ????

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??

• ???????,?????????,??????????????,??????
  ?,?????????????,????????????????????

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DNA Damage

• a.single base changes
• 1.Deamination
• 2.Replication error
• b.structural distortions
• 1.Ultraviolet irradiation
• 2.Alkylation
• 3.Depurination

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a.single base changes??????,????????DNA????

• 1.Deamination
• C???????U,U-G????C-G,????????

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• 2.Replication error
• C???????A,??????????,?????????

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b.structural distortions?????

• 1.Ultraviolet irradiation
• ??????,?A?T???????,??T?T?????,??????T???T-T???,?DN
  A????????????

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• 2.Alkylation(???)
• ????????(-CH3)??DNA????

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• 3.Depurination???????????????,?????????,?????

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DNA repair

• Direct repair
• Excision repair
• ?Mismatch repair
• Recombination repair
• ?SOS system

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Direct repair

• Photoreactivation(?????)
• ?????T-T-?????,??????,???????? T-T-??????,????????
  ?,?????DNA?
• Methyl transferase(?????)
• DNA??????????,??????????

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Excision repair

• ??????DNA??,?????????DNA,??????????

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Mismatch repair

• ?DNA???,????????,??????????,???Mismatch
  repair??????,???????,??????

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Recombination repair

• ??????DNA????,??????????,DNA????????????????
• ??????,?????DNA????,?????DNA?????,?????????????DNA
  ??
• ????????????, ????(Excision repair)???????,???????
  ???DNA?????????????

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SOS system

• ?SOS??????????,????????????????,??????????DNA????
  ???,???????????,??????????,????????DNA???????????
• ????????
• SOS???????,?????????????,??????????????

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??
TYPE OF DAMAGE events/cell/day of total daily damage
Single-strand break 120,000 50.9
N7-MethylGuanine 84,000 35.6
Depurination 24,000 10.2
Oxidized DNA 2,880 1.2
Depyrimidation 1,320 0.5
Cytosine deamination 360 0.2
Double-strand breaks 9 0.01
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??

• ?DNA???????????
• ??????(Xeroderma pigmentosum)
• ??????????,????T-T???
• ??????(Blooms syndrome)
• ??DNA???,???????DNA,????????
• ??????(Hereditary nonpolyposis colon
  cancerHNPCC)
• ???????????

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• ??????,?????????,?????????DNA,?????????????
  ???????????????,????????????,???????,????????????
  ,????,?????????

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????

• Gene VII, Chapter 14, Oxford University Press
• ?????, ????, ????