LIFESCI 3 Lecture Notes - Lecture 15: Helicase, Stem-Loop, Base Pair
Document Summary
So protein needs to distinguish which base on which strand: 3 steps: initiation, elongation, termination initiation is the longest, most important step; costs most energy. Rna polymerase: core enzyme + sigma factor = holoenzyme, core enzyme and rna pol(cid:455)(cid:373)e(cid:396)ase (cid:449)o(cid:374)"t fu(cid:374)(cid:272)tio(cid:374) (cid:449)ithout sig(cid:373)a fa(cid:272)to(cid:396, sigma factor carries rna polymerase to different regions of the genome looking for promoter regions. Rna p does(cid:374)"t do a good jo(cid:271) looki(cid:374)g fo(cid:396) se(cid:395)ue(cid:374)(cid:272)es; i(cid:374)stead i(cid:374)itiate o(cid:374)l(cid:455) a little o(cid:374) its sigma factor scans dna for promoter regions own. But to initiate in an efficient manner needs sigma factor. Pk promoter region: promoter (cid:396)egio(cid:374): (cid:862)upst(cid:396)ea(cid:373)(cid:863); closer to 5" end of coding strand. 10 and -35 boxes: several nucleotides are conserved -> usually similar in evolutionary similar organisms. Other places have less perfect consensus -> sigma factors are less likely to bind there conserved sequences serve as consensus sites/perfect binding sites for sigma factor the(cid:396)e"s a -35 and -10 sequence for each sigma factor.
