MIC 102 Lecture Notes - Lecture 8: Exocytosis, Consensus Sequence, Rifampicin
23 Oct 2017
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Document Summary
Rna polymerase has 5 subunit, plus requires a sigma factor for initiation: alpha = assembly of rnap and promotor interaction, beta = contains active center, omega = assembly and stability. Rnap requires a sigma factor to bind to a promoter sequence in dna: sigma factor opens rnap allowing it to bind. Alpha and sigma subunits recognize promotor sequences: -10 and -35 regions, these numbers aren"t exact. Consensus sequence; the more closely a sequence fits the consensus, the more affinity. Once rnap is bound in a closed complex, it will slowly open up to a 12bp open bubble. Transcription will start and fail possibly several times before rnap can escape the. It will start advancing and opening the bubble to 18bp promotor and drop the sigma factor. 40 and -60 up stream elements, as well as other accessory transcription factors, can influence abortive transcription. Some genes/operons contain more than 1 promotor sequence.
