Chpt. 8 Gene Expression

Chpt. 8 Gene Expression - Essential CellBiology...

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Chapter 8 Control of Gene Expression Essential Cell Biology Third Edition Copyright © Garland Science 2010
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Control of Gene Expression Transcription factors and regulatory DNA sequences Initiation of eukaryotic transcription Eukaryotic gene expression is regulated by many regulatory proteins (factors) A single regulatory protein can function in the regulation of multiple genes
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Regulation of Transcription: Eucaryotes vs. Procaryotes
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Figure 8-8 Essential Cell Biology (© Garland Science 2010) Figure 8-8 Bacterial Gene expression can also be controlled with activator proteins . An activator protein binds to a regulatory sequence on the DNA and then interacts with the RNA polymerase to help it initiate transcription. Without the activator, the promoter fails to initiate transcription efficiently.
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Figure 8-7 Genes can be switched on and off with repressor proteins . Example of bacterial trp operon: If the concentration of tryptophan inside the cell is low, RNA polymerase ( blue ) binds to the promoter and transcribes the five genes of the tryptophan operon ( left ). If the concentration of tryptophan is high, however, the repressor protein ( dark green ) becomes active and binds to the operator ( light green ), where it blocks the binding of RNA polymerase to the promoter ( right ).
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Figure 8-3 Essential Cell Biology
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Chpt. 8 Gene Expression - Essential CellBiology...

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