BIOL 1F90 Lecture Notes - Lecture 17: Nucleoside Triphosphate, X-Ray, Cancer Cell
1 Dec 2016
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Dna polym makes less mistakes bc: correct h bonding more stable, a(cid:272)ti(cid:448)e site (cid:449)ould(cid:374)"t usuall(cid:455) for(cid:373) (cid:271)o(cid:374)ds if (cid:373)is(cid:373)at(cid:272)hed, proofreading activity- detection when mis-paired base happens; removes w/ 3" to 5" exonuclease fxn. Telomeres- regions at end of linear euk chromosomes; short sequence (ttaggg-6nt) Dna polym makes in 5" to 3"; requires primer: cant copy end of lagging, rna primer would have to be removed if placed at last base, makes single 3" overhang. Makes linear chromosome to become shorter every replication round. Telomerase- attaches many new copies of dna to end of chromosome to prevent shortening. Made of protein/rna: complementary to telomeric repeat seq; binds to 3" overhang/serves as template. Telomerase binds/synthesizes new telomeric dna then moves down to repeat: occurs many times to lengthen 3" end, longer 3" overhang provides an upstream site for new rna primer to be made & dna copied by dna polymerase.
