Lecture.14.Fall.2013

Ends trans termination of transcription extrinsic rho

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Unformatted text preview: iption ends at a 40-bp long termination signal sequence • This sequence forms a hairpin loop structure that destabilizes the protein’s interaction with the RNA molecule • The RNA is released, and the polymerase releases the DNA as well. ends trans Termination of Transcription extrinsic • Rho-dependent termination: • Some genes require the presence of an additional protein factor (rho) to terminate transcription • rho encodes a helicase (unwinds helices) Eukaryotic Transcription: How it differs • Occurs in the nucleus (bacteria have none) • Multiple RNA polymerases • More complex promoter regions • Much more highly regulated – Enhancer sequences Eukaryotic Transcription: How it differs bacteria no chrom only supercoil • Chromatin must be remodeled to allow transcription factors access to the DNA • Eukaryotic transcripts undergo extensive processing to form a mature mRNA molecule trans and trans simultaneous in bacteria right away Eukaryotic Transcription: How it differs • Occurs in the nucleus (bacteria have none) • Multiple RNA polymerases • More complex promoter regions • Much more highly regulated – Enhancer sequences Eukaryotic Multiple RNA polymerases (RNPs) • Three different RNA polymerases – RNP I transcribes rRNA ribosomal – RNP II transcribes mRNA mess – RNP III transcribes tRNA and some rRNAs trans • So, why are death cap mushrooms bad for you? • Why so specific to the liver? (Make a guess.) stop making protein Eukaryotic Transcription: How it differs • Occurs in the nucleus (bacteria have none) • Multiple RNA polymerases • More complex prom...
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This document was uploaded on 02/25/2014.

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