BIOS-115 Lecture Notes - Lecture 12: Hydroxylamine, Deamination, Hydroxy Group
4 Nov 2018
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Document Summary
Chemical mutagens: base analogs- look similar to normal dna bases e. g. 5bu (5-bromouracil, base-modifying agents: changes the structure of the base e. g. deaminating agents, hydroxylation. Nitrous acid leads to loss of amino (deamination) agents and alkylation agents. Methylmethane sulfonate leads to addition of methyl group (alkylation) Repair of alkylation damage: type of direct reversal repair, specialized enzymes, e. g. in e. coli methylated o6 guanine repaired by o6- methylguanine methyl transferase. The following nucleotide sequence is found in a short stretch of dna. Chemical mutagens: intercalating agents: insert/intercalate between dna bases. Mismatch repair: dna pol(cid:455)(cid:373)erase has 3"-5" e(cid:454)o(cid:374)uclease proofreadi(cid:374)g activit(cid:455) During dna replication can go back, detect mismatched base pairs, remove incorrect base. Base excision repair: type of excision repair, repairs damaged single bases, e. g. depurination and deamination, mechanism, glycosylase removes damaged base, other enzymes cleave backbone, repair dna polymerase & ligase fill gap, using opposite strand as template. Single molecule technique that will create a topographic image.
