LIFESCI 3 Lecture Notes - Lecture 12: Chromosome, Point Mutation, Pyrimidine
Document Summary
4 tubes for a, g, c, t. Fragments ending where a ddntp was incorporated is generated. Read with autoradiogram: separate all fragments by gel electrophoresis, newer method: Base damage by oxidizing agents (has both intrinsic & extrinsic sources: spontaneous base damage by hydrolysis. C ofte(cid:374) dea(cid:373)i(cid:374)ated i(cid:374)to ura(cid:272)il (cid:894)does(cid:374)"t (cid:271)elo(cid:374)g i(cid:374) dna(cid:895) -> repair mechanism that reverse lesion. G often depurinated (loses nitrogenous base; nucleotide turned into a sugar phosphate without base) C deaminated to t (less obvious, since t is a normal base in dna: uv light - thymine dimers. When uv light hits two adjacent t, causes them to fuse -> thymine dimer. Chemicals wedged in dna backbone -> distortion in double helix. Often causes insertions/deletions/poi(cid:374)t (cid:373)utatio(cid:374) (cid:894)dna pol (cid:272)a(cid:374)"t properly repli(cid:272)ate intercalated dna) & strand break: base analogs. 5-bromouracil can pair with a or g, accidentally incorporated during dna synthesis (pairs with a in keto form, g in enol form)
