Chapter 11 - Transcription and Translation

Control how much of each variety of sigma is produced

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Unformatted text preview: ch variety of sigma is produced control gene expression REMEMBER o o RNA is made from 5 to 3 RNA synthesis begins at transcription start site first nucleotide is at position +1 2 o o Promoters are where RNA polymerases binds DNA upstream (5 ) of transcription start site (-10 and -35 elements) Downstream in 3 direction Prokaryotic Promoters Continued o o o o o Transcription occurs at certain points and so does termination Termination sequences: found close to the ends of coding sequences In prokaryotes, there are 2 types: rho independent terminators and rho dependent terminators Rho dependent terminators use of a factor called rho which actively unwinds the DNA-RNA hybrid fromed during transcription It moves in the 3 direction, releasing the newly synthesized RNA if it catches up to RNAPol, transcription stops Eukaryotic Transcription o o o o o o o o o o o o 3 types of RNA polymerases in eukaryotes Most rRNAs are transcribed by RNA polymerase I mRNAs are transcribed by RNA polymerase II tRNAS are transcribed by RNA polymerase III the RNAPols are multisubuint complexes more subunits than the prokaryotes, but core structure is very similar example: yeast RNA Polymerase II regions structurally homologous with prokaryotic RNA polymerase large variety of accessory proteins transcription factors transcription factors: regulate activity of RNA polymerases binding of RNA polymerase and DNA, initiation of transcription, elongation and termination transcription facto...
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