LIFESCI 3 Chapter Notes - Chapter 15.1-15.3: Sigma Factor, Ribonucleoside, Peptide
Document Summary
Is catalyzed by dna-dependent rna polymerases, which use. Factor to recognize and bind the promoter during initiation. Eukaryotic cells have three types of rna polymerases. encoding rrnas and small functional rnas transcribes protein-coding genes to make mrna. Various naturally occurring small molecules inhibit polymerase enzymes and can be used to detect which polymerase produces specific types of rna. Much of the regulation of protein levels in both bacterial and eukaryotic cells occurs during the early stages of transcription. Rna polymerase first forms a closed complex on promoter dna, a readily reversible state that is not yet capable of transcription. On conversion of the closed complex to a transcription-competent open complex, either through spontaneous isomerization or by atp-dependent conformational change, rna polymerase begins rna synthesis without requiring a primer. Transcription initiation requires promoter clearance, in which the rna polymerase moves beyond the promoter region of the dna to begin rapid elongation of the transcript.
