lecture 7 070908 1p

lecture 7 070908 1p - LECTURE 7: 9 July 2008 Prokaryotic...

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Unformatted text preview: LECTURE 7: 9 July 2008 Prokaryotic Transcriptional Regulation 1. Brief review on Prokaryotic Translation 2. Three ways to control gene expression 3. Transcriptional control 4. Organization of operons 5. Classic example of operons: The Lac and Trpoperons Midterm 1 will be given back after Fridays lecture! Midterm 2: Friday July 18, 2008 FRANZ 1178 9-11am L S 3 L S 3 Protein synthesis occurs in 3 stages Aminoacyl-tRNA= activated tRNAwith attached amino acid Peptidyl-tRNA= growing peptide chain attached to tRNAin P site The growth of the nascent polypeptide during translation 3 Important Sites in the Ribosome Aminoacyl-tRNA= activated tRNAwith attached amino acid Peptidyl-tRNA= growing peptide chain attached to tRNAin P site EF-Tudelivers next aminoacyl-tRNA EF-G drives translocation of the ribosome RF factors play an essential role in termination Control of gene expression in prokaryotic cells: are genes always ON ? 1. Transcriptional 2. Translational 3. Post-translational Various ways of controlling gene expression: Control of Gene Expression h Translational control : h Preventing an mRNA from being translated, can affect elongation or initiation h Post-translational control : h Some proteins are made in an inactive form and need to be activated h Remember back to various ways of modifying proteins Transcriptional Control h Proteins can interact and bind to regions of DNA to affect transcription The interplay of activators and repressors Promoter RNA +1 Transcription Activator Transcription Repressor Protein-coding region Transcription start site Untranslatedleader sequence RNA Polymerase DNA Negative control vs. positive control h Negative control h Operon is expressed in absence of repressor h Great example: the Lac operon h Positive control h Operon is not expressed except in presence of an activator...
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This note was uploaded on 07/12/2008 for the course LS 3 taught by Professor Lin during the Summer '06 term at UCLA.

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lecture 7 070908 1p - LECTURE 7: 9 July 2008 Prokaryotic...

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