Lecture_22_DulaiS09_LacOperon

Lecture_22_DulaiS09_LacOperon - Lac Operon A complex type...

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Lac Operon A complex type of gene regulation
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How is gene expression regulated in prokaryotes? • Ex. The operon – unique to prokaryotes · set of functionally related genes (+ promoter and operator) whose expression is regulated as one What are the standard components of an operon? 1) operator sequence of DNA along operon where regulatory protein binds to control transcription of operon genes · operator is NOT a gene; is a regulatory protein binding site Ex. Lac operon · gene for regulatory protein that binds at operator NOT part of operon Figure 15.10 Part of bacterial chromosome
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Repeat • Some genes are part of an operon – Lactose operon – Trypophan operon • Other are like human genes where one promoter helps make one gene product.
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What are the standard components of an operon? 2) promotor – DNA regionto which RNA polymerase binds. ·promotor is NOT a gene; is a binding site Ex. Lac operon · Test yourself: What does RNA polymerase do?? 3) structural genes – DNA that codes for proteins whose expression regulated via operon. How many genes in lac operon? Where are they located with respect to the operator and promotor? Figure 15.10 Part of bacterial chromosome
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Gene regulation in prokaryotes: operons Promoter: DNA sequence (i.e., not a gene ) that is the RNA polymerase binding site to initiate transcription. Operator: Controls the binding of RNA polymerase to promoter region Structural genes: Genes that codes for proteins (e.g., enzymes) The regulation of operons may also involve: Regulatory gene: Codes for a repressor (protein) that binds to the operator, preventing transcription. Inducer: Binds to repressor, inhibiting it An operon is a unit of DNA sequences (some are not genes) including at least: an operator , a promoter , and one or more structural genes that are controlled as a unit to produce one mRNA.
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Ex. Lac operon
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This note was uploaded on 11/18/2010 for the course SS 101 taught by Professor Denver during the Spring '10 term at Alabama.

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Lecture_22_DulaiS09_LacOperon - Lac Operon A complex type...

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