BS 161 1st Edition Lecture 30 Outline of Last Lecture I Transcription translation Outline of Current Lecture II Transcription translation continued Current Lecture promoter the DNA sequence where RNA polymerase attaches terminator the sequence signaling the end of transcription three stages of transcription initiation elongation termination transcription factors mediate the binding of RNA polymerase transcription initiation complex the completed assembly of transcription factors and RNA polymerase II bound to a promoter TATA box crucial in forming the initiation complex in eukaryotes TATA box is at 25 relative to the RNA synthesis start site as RNA polymerase moves along the DNA it untwists the double helix 10 to 20 bases at a time transcription progresses at a rate of 40 nucleotides per second in eukaryotes a gene can be transcribed simultaneously by several RNA polymerases the mechanisms of termination are different in bacteria and eukaryotes in bacteria the polymerase stops transcription at the terminator in eukaryotes the polymerase continues transcription after the pre mRNA is cleaved from the growing RNA chain and the polymerase eventually falls off the DNA DNA polymerase requires a primer RNA polymerase does not post transcriptional processing during RNA processing both ends of the primary transcript are usually altered introns noncoding sequences exons other regions
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