Gene Regulation in Prokaryotes

Flashcards covering key concepts in gene regulation in prokaryotes, such as operon types, function, and gene expression mechanisms.

Differential Expression of Genes

The ability to turn genes on or off, allowing organisms to conserve energy and achieve cell specialization.

Feedback Inhibition

A regulatory mechanism where the end product of a process inhibits an earlier step in the pathway.

Bacterial Operon

A cluster of genes under the control of a single promoter, including regulatory sequences.

Components of a Bacterial Operon

Includes the promoter, operator, and structural genes.

Repressible Operon

An operon that is usually on but can be inhibited (turned off) by a corepressor.

Inducible Operon

An operon that is usually off but can be activated (turned on) by an inducer.

trp Operon

Regulates the synthesis of tryptophan; transcription occurs when tryptophan levels are low.

lac Operon

Regulates the metabolism of lactose; transcription occurs when lactose is present and glucose is absent.

Repressor Protein Activation State (lac and trp Operons)

The lac operon repressor is inactive in the presence of lactose, while the trp operon repressor is active in the presence of tryptophan.

Negative Gene Regulation

A form of regulation where a repressor inhibits gene expression.

Positive Gene Regulation

A form of regulation where an activator enhances gene expression.

lacI

A gene that codes for the repressor protein in the lac operon.

CRP (CAP)

A protein that acts as an activator for the lac operon in response to low glucose levels.

Transcription Level with High Tryptophan (trp operon)

Transcription is low or turned off when tryptophan levels are high.

Transcription Level with Low Lactose (lac operon)

Transcription is low or turned off when lactose levels are low.

Transcription Level with High Lactose (lac operon)

Transcription is high when lactose is present.

Operator

A DNA sequence in an operon that interacts with repressor proteins to control transcription.

Promoter

The sequence of DNA where RNA polymerase binds to initiate transcription.

Structural Genes

Genes within an operon that code for proteins needed for a specific metabolic pathway.

Response to Environmental Change

Bacteria regulate transcription based on environmental changes to adapt appropriately.