BIOL 202 Lecture Notes - Lecture 23: Identification Key, Centromere, Neurospora
Document Summary
Transcription initiation is the most important process in prokaryotes. Prokaryotic metabolic genes are organized into operons. Sigma factor of rna polymerase: binds to consensus sequences, placement of sigma factor determines the transcriptional initiation start site initiates transcription by recruiting the subunits of rna polymerase. The default form of most genes is on". Rna polymerase can"t bind to the promoter transcription can"t happen: mechanism (with lactose): lactose binds to the lac repressor protein the lac repressor protein enters a non-dna-binding incompetent state the lac repressor protein dissociates from dna. Jacob & monod method: affected the gene mutant strains (with altered beta galactosidase and permease activity) were chosen. Ii: cap is bound to camp, cap is activated and in its dna-binding form, cap binds to the region upstream of the lac operon promoter, cap helps to recruit rna polymerase to the lac operon promoter. Iii: cap can"t bind to camp, cap is inactive, cap can"t activate transcription.