Regulation of Prokaryotic Gene Expression

Prokaryotic Regulation

The process by which bacteria conserve resources and energy by producing genes/products only when needed.

Operon

The entire stretch of DNA required for enzyme production, comprising several parts including the operator, repressor, regulatory gene, and promoter.

Repressor

A protein that binds to the operator to block RNA polymerase access to a gene, preventing transcription.

Corepressor

A molecule that binds to the repressor and activates it, halting further production of a substance in repressible operons.

Inducible Operon

An operon that requires an inducer to inactivate the repressor and induce transcription.

TRP Operon

A repressible operon that synthesizes tryptophan and is inhibited by the presence of excess tryptophan.

LAC Operon

An inducible operon that produces lactase, the enzyme that breaks down lactose, only when lactose is present.

Positive Gene Regulation

When a protein binds to the promoter, it increases the rate of transcription, functioning like a volume knob instead of an ON/OFF switch.

cAMP

Cyclic AMP, a molecule that accumulates when glucose is scarce and is involved in the positive control of the lac operon.

CRP (CAP)

Cyclic AMP receptor protein, an activator that binds to DNA to stimulate transcription, involved in the regulation of the lac operon.

Feedback Inhibition

A regulatory mechanism where the production of a product inhibits its further production when levels are sufficient.

Anabolic Pathway

A metabolic pathway that builds molecules and operates when the levels of the molecule decrease.

Catabolic Pathway

A metabolic pathway that breaks down molecules and operates only when a substrate is present.

Transcription

The process by which RNA polymerase binds to the promoter to synthesize RNA from a DNA template.

Negative Gene Regulation

A type of regulation where the active form of the repressor blocks transcription.