Biochemistry 2280A Lecture Notes - Lecture 16: Exonuclease, Chromosome Abnormality, Glycosidic Bond
23 Dec 2017
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Document Summary
Dna damage = unintended changes in dna sequence/ structure that is heritable: copying mistakes. Occur made by dna polymerase (1 mistake per 10^7 bp) Mismatched bp > change in sequence > permanent mutation occurs in one of the dna helix after next round of replication: depurination. Acid promotes loss of purine a/ g base. Results in breakage of glycosidic bond, but intact backbone, but with an empty site abasic site. Abasic site causes polymerase to stall which recruits a transletion dna polymerase. Transletion polymerase is able to pass by abasic site by either skipping a base, or randomly incorporating a base. Resulted mutation is either missing a base, or has a wrong base. Regular polymerase resumes for the rest of replication: deamination. Amine group of cytosine is replaced with carbonyl which changes cytosine to a uracil. When polymerase reads this u , it will just pair it with an a they pair well tgt.
