Biochemistry 2280A Lecture Notes - Lecture 2: Operon, Enzyme
13 Oct 2015
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Document Summary
Why is there an rna step in the gene expression: provides an amplification that can contribute to gene expression (can increase the number of the gene, since rna can be degraded, expression of a gene can be stopped quickly (can turn a gene off in certain conditions, rna provides additional opportunities for regulations (rna processing and export from the nucleus) Steps in the initiation of transcription: rnap holoenzyme binds to the promoter (forms a closed complex, rna polymerase unwinds the dna strands around the start site open complex, the first ntp is brought to the template no primer is required, using atp, gtp, ctp and utp as substrates, chain elongation proceeds in a 5" 3" direction following base pairing rules, after 5 10 addition of nucleotides, the transcription bubble starts moving downstream with eh dna reanneling behind, rna synthesis proceeds until a terminator is reached and rna polymerase falls off, sigma rebinds rnap and the cycle is repeated.
