10 PLG Control of Gene Expression in Bacteria

Flashcards for understanding key concepts related to gene expression control in bacteria, particularly focusing on operons and their regulatory mechanisms.

Operon

A series of genes transcribed together under control of a single promoter.

lacI gene

Encodes a transcriptional repressor that prevents transcription of lacY and lacZ when bound to the operator.

lacY gene

Encodes a protein necessary for lactose uptake.

lacZ gene

Encodes a protein needed to metabolize lactose.

Transcriptional repressor

A protein that inhibits gene transcription by binding to the operator region of DNA.

Operator

A DNA sequence where the repressor binds, blocking transcription of the operon.

Inducer exclusion

A mechanism where high glucose levels prevent lactose import by inhibiting galactoside permease.

cAMP (cyclic AMP)

A small molecule that, when present, allows CAP to activate transcription of the lac operon.

CAP (catabolite activator protein)

A transcriptional activator that enhances the binding of RNA polymerase to the promoter of the lac operon.

Negative control

Regulation of gene expression by inhibiting transcription.

Global Regulation

The control of multiple operons or genes simultaneously, often in response to environmental changes.

Sigma factor

A protein that assists RNA polymerase in recognizing the promoter region of a gene.

Regulon

A group of genes regulated by a common regulatory protein, similar to operons but often wider in scope.

Tryptophan operon

An operon that encodes proteins required for the biosynthesis of the amino acid tryptophan.

Gene expression regulation

The mechanisms that control the timing and amount of protein production from genes.