BIOL 1000 Lecture Notes - Lecture 9: Aspartic Acid, Cytoskeleton, Cell Wall
31 Jan 2013
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May happen because of uv light or a cytisine becoming uracil by spontaneous de-amination: cnh2 cooh, another way is that dna polymerase accidentally inserts u into dna (as dutp [instead of dttp]) Note: many chemotherapeutic drugs affect the cell so that it increases the amount of dutp. If dutp [] is increased by drugs, increase level of u in dna there is a high degree of repair. The repair system is then overwhelmed and this leads to dna fragmentation and then death of the cell. This process targets fast dividing cells (cancer, hair etc. ) and that"s why cancer patients are bald. I. e. via uracil-dna-glycosylase: enzyme removes a small gap of nucleotides. This is like when rna primase is has to be removed: fill in gap by dna poly. Proofreading by dna polymerase: enzyme will notice that there is not good h bonding and it will reverse, splice and repair the base, note: retrovirus polymerases are highly mutagenic.
