Biochemistry 2280A Lecture Notes - Lecture 16: Cutaneous Condition, Covalent Bond, Uracil
16 Jan 2018
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Dna damage=any unintended physical or chemical change in dna. Changes in dna can be neutral, beneficial, or deleterious. Dna tries to preserve the dna by fixing damage, greater chance that dn damage is deleterious. Overview: damaged segment is removed and exposes the bottom strand that is used as a template to replace the correct nucleotides by complementary base pairing and nicks are sealed by ligase. Dna polymerase makes a error every 107 nucleotides. Dna polymerase has proofreading abilities, but sometimes misses them, and is fixed by mismatch repair system. Insertion- extra bases is added into newly synthesized strand, newly synthesized strand is longer than template strand. Deletion- newly synthesized strand is missing a base, it is shorter than the template strand. If dna is not repaired before the next round of replication, the strand with the mismatched base would be used as the template strand, and result is a replacement of base pair.
