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Gene Regulation
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The simplest and most well understood model of the regulation of individual genes is found in
prokaryotes.
We will study two examples of gene control in E. coli ; a bacteria found in the human digestive tract
The General Layout of an Operon
The Lac Operon in e. coli
Controlling The Lac Operon in e. coli
(repressors, inducers & activators)
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With no proteins bound to either the operator or activator regions, RNAP is free to bind to the
promoter and transcribe the genes
What would be the problem with having the lac operon on all the time?
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Describe the role of the repressor protein in the lac operon.
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Since glucose is the preferred energy source for cells,
If glucose levels are LOW
If glucose levels are HIGH,
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How does the lac operon detect glucose levels from within the nucleus? __________________________
Describe the role of Catabolite Activator Protein (CAP) in the lac operon.
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Summary of Lac Operon Control (CAP no included)
The Trp Operon in e. coli
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If ingested levels of the amino acid tryptophan are low, e. coli is ableto synthesize it on its own.
When tryptophan levels are low, the try operon is turned on to make the enzymes necessary to
synthesize more.
What would be the problem with having the trp operon on all the time?
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Describe the role of repressor protein in the trp operon.
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What is the main difference between positive and negative gene regulation?
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On your own, summarize
the post transcriptional
and post translational
control cells have over
their genes using your
textbook