BIOL308 Lecture Notes - Lecture 8: Guanine, Mutation, Homologous Recombination
30 May 2017
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1: replication errors: that weren"t detected by dnap1/2 and proofreaders. 2: spontaneous changes: due to depurination or deamination. Notes: happens more in sperm . vs. egg, dnap makes 1 mistake per 109 base pairs (3 mistakes per cell division) and since most dna is non-coding/conserved, mutations don"t usually result in detrimental effects, repaired by multiple redundant mechanisms. D: depurination: due to hydrolysis of the n-glycosyl linkage removing a base (apurinic site) and cause a frameshift in one of the daughter dna. A: alkylating chemicals (nitrosamines, n-methyl-n1-nitro-n-nitroguanidine): alkyl groups are added, o is methylated on c6 of guanine where g:c o6-methylguanine: t. B: reactive oxygen species (h2o2, o2-, oh through ionizing radiation and chemical agents): C: base analogues: 5-bromouracil where c:g t:g. D: nonionizing radiation: 260n, is absorbed by bases and fuses pyrimidines. T dimer: cyclobutane ring that links c5 and c4 of adjacent t"s and distorts the backbone. E: ionizing radiation (x-rays, gamma rays): which breaks dna.
