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Operon Control of Gene Expression
Operon Control of Gene Expression
An operon contains a collection of genes which
are switched on and off together, as a unit.
Operon Control of Gene Expression
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Here is the Tryptophan operon OR trp operon
Operon Control of Gene Expression
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These five proteins allow the bacteria to
synthesize trp ... and therefore survive.
Operon Control of Gene Expression
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The trp operon
Operon Control of Gene Expression
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The regulatory gene codes for the repressor
Operon Control of Gene Expression
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Tryptophan interacts with the repressor to change it’s
conformation. It can now bind with the operator.
Operon Control of Gene Expression
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In the presence of trp the repressor binds to
the operator, and blocks RNA polymerase
Operon Control of Gene Expression
An operon is a system which controls how genes
are switched on and off together, as a unit.
It is not the proteins that are produced that
define an operon, an operon is a mechanism
of control. An operon always contains several
structural genes, an operator, and a promoter.
Operon Control of Gene Expression
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Lactose operon OR lac operon
Operon Control of Gene Expression
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The lac operon here is inactive, because the
repressor is connected to the operator.
Operon Control of Gene Expression
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The lac operon here is active. A single transcript is
produced, with multiple start and stop codons.
Operon Control of Gene Expression