BIOLOGY 151 Lecture Notes - Lecture 6: Rna Polymerase Ii, Pribnow Box, Protein Subunit
Document Summary
Initiation and termination of transcription: transcription in initiated at a promoter sequence and ends at a terminator sequence. The tra(cid:374)script is sy(cid:374)thesized i(cid:374) a 5" to 3" directio(cid:374): both dna strands serve as templates for transcription. Initiation is the first phase of transcription: rna polymerase cannot initiate transcription on its own, sigma is a protein subunit that must first bind to the polymerase. Bacterial promoters: bacterial promoters, are compromised of 40-50 base pairs, have two key regions = -10 box and -35 box, the -10 box (pribnow box) Is found 10 bases upstream from the transcription start site (the +1 site: consists of the sequence tataat, the -35 box. Is 35 bases upstream from the +1 site: consists of the sequence ttgaca, all bacterial promoters have a -10 box and a -35 box, the remainder of the promoter sequence varies. Each type allows rna polymerase to bind to a different type of promoter therefore a different kind of gene.