BIOL 1000 Lecture Notes - Lecture 7: Pyrimidine Dimer, Ultraviolet, Complementary Dna
21 Jan 2018
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Document Summary
Dna damage one strand or both. Various natural and synthetic chemicals can cause this including: Ultraviolet radiation (e. g. can cause thymine dimer). During replication dna polymerase proofreads and repairs errors in the complementary dna as. Special enzymes (glycosylases) scan for and recognize specific base alterations. Then nucleases cut the dna on either side of error. Then incorrect nucleotide is removed (excised) dna polymerase fills in the gap with new nucleotides. Then dna ligase attaches new piece to existing dna. Summary: other sets of enzymes called nucleases cut either side and then dna polymerase fills it up w/ correct dna. Damaged or incorrect nucleotides are structurally and/or chemically different from undamaged. It takes ti(cid:373)e to repair dna, so (cid:272)y(cid:272)le slower (cid:271)ut .
