BIO130H1 Study Guide - Dna Repair, Dna Polymerase, Ataxia Telangiectasia
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BIO130H1 Full Course Notes
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Document Summary
Dna damage can be removed by more than one pathway. There are two pathways that allow for the damage in dna to be excised: base excision repair. It involves a battery of enzymes called. Dna glycolases, each of which recognize a specific altered base (e. g. deanimated. Cs & depurinated as, oxidized bases, bases with open rings, c-c double bonds accidentally converted into c-c single bonds) in dna and catalyze its hydrolytic removal. In order to find an altered base, a key step is an enzyme-mediated flipping out" of the altered base which allows dna glycolase to assess the damage and evaluate each base. Once the enzyme finds a damaged base, it is removed from its sugar. The missing tooth" created by dna glycolase is recognized by the. Ap endonucleases which cuts the phosphodiester backbone, after which the damage is removed and the resulting gap is fixed.
