Chapter 16 - Chapter 16 Transcription and Translation 16.1...

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Chapter 16 Transcription and Translation 16.1: Transcription in Bacteria: o Transcription occurs when RNA polymerase matches the base in a ribonucleotide triposphate with the complementary base in a gene, a section of DNA o Once a matching ribonucleotide is bound, RNA polumerase catalyzes the formation of a phosphodiester bond between the 3’ end of the growing mRNA chain and the new ribonucleotide o Only one of the two DNA strands is used as a template and transcribed by RNA polymerase o RNA Polymerase Function Initiation in bacteria Detachable protein subunit called sigma must bind to RNA polymerase before transcription can begin Holoenzyme, RNA polymerase and sigma o Consist of a core enzyme Contains the active site for catalysis, and other required proteins Promoters, specific sections of DNA where the holoenzyme bound o Sections of DNA where transcription begins Sigma is responsible for guiding RNA polymerase to specific locations where transcription should begin -10 box: TATAAT, occurs about 10 bases from the point where RNA polymerase starts transcription o downstream: where DNA is located in the direction that RNA polymerase moves during transcription -35 box: TTGACA, upstream from the start of the mRNA transcription begins when sigma binds to the –35 and –10 boxes Sigma, and not RNA polymerase makes the initial contact with DNA that starts transcription in bacteria Sigma is a regulatory protein Once sigma binds to a promoter, the DNA helix opens and creates two strands of single-stranded DNA Template strand is threaded through a channel that leads to the active site inside RNA polymerase
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This note was uploaded on 03/19/2008 for the course BS 111 taught by Professor Patterson during the Fall '05 term at Michigan State University.

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Chapter 16 - Chapter 16 Transcription and Translation 16.1...

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