Lecture 101 Rec DNA Chiu 2008

Lecture 101 Rec DNA Chiu 2008 - Chi-hua Chiu Dept. of...

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Chi-hua Chiu Dept. of Genetics Office Hours: Tuesdays, 12:45-1:45 Douglass Campus MSLC No Office hours Tuesday November 25 No Office hours Tuesday November 25. Copy of important figures (not in your book) and lecture guide will be on reserve at the MSLC.
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5’ 3’ Non-coding promoter DNA Non-coding enhancer DNA Can control transcription (generation of RNA) 3’ 5’ Transcription, post-transcriptional processing 5’ 3’ Processed mRNA only contains exon sequences. Introns spliced out. translation Protein is a string of amino Acids. It is mobile in the cell.
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Prokaryotes e.g. Escherichia coli (E. coli) lac operon (Jacob and Monod) operon – group of genes that are coordinately controlled and transcribed as a unit
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The lac Operon Repressor gene - constitutive structural gene that codes for a repressor protein Promoter – site on DNA where RNA polymerase binds Operator – site on DNA that is blocked by binding of the repressor protein lac Z, lac Y and lac A – structural genes that code for enzymes used in lactose metabolism
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Lactose absent lacZ , lacY , lacA are not transcribed. i.e. not expressed.
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What happens if lactose is present? 1. Some lactose enters the cell and is converted to allolactose 2 Allolactose binds to the repressor and inactivates it. This is called 2. “De-repression”. 3. Allolactose is the inducer for the lac operon.
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Lactose present
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operon good example of Transcriptional level control Specifically, negative control : 1. control is by a negatively acting repressor
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Lecture 101 Rec DNA Chiu 2008 - Chi-hua Chiu Dept. of...

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