Gene Expression and the Lac Operon Flashcards

A set of vocabulary flashcards covering the concepts of gene expression regulation, focusing on eukaryotic mechanisms and the specific function of the Lac operon in E. coli.

Gene Expression

The precisely regulated activation or deactivation of a gene in response to a signal.

Transcription Factors

Proteins that bind to DNA regulatory elements to control gene transcription.

DNA Regulatory Elements

Regulatory nucleotide sequences that enable the precise regulation of transcription in each cell type.

Lactose (Lac) Operon Model

The first model based on actual data to explain how cells regulate gene expression, describing how prokaryotes regulate transcription.

Operon

A group of related genes clustered together on the prokaryotic (Archaea and Bacteria) chromosome that code for related proteins performing a cellular function.

Escherichia coli (E. coli)

A bacterium inhabiting the lower human intestine that utilizes the Lac operon to metabolize lactose (milk sugar).

Polycistronic mRNA

A single mRNA molecule produced that codes for all three proteins in the Lac operon.

Lac Z Gene

A gene in the Lac operon that codes for the Beta-Galactosidase enzyme.

Beta-Galactosidase

An enzyme that cleaves lactose to produce galactose and glucose.

Lac Y Gene

A gene in the Lac operon that codes for the membrane transport protein, Permease.

Permease

A membrane transport protein that imports lactose; E. coli has $\ge 300$ of these proteins in its cell membrane.

Lac A Gene

A gene in the Lac operon that codes for the Transacetylase enzyme.

Transacetylase

An enzyme that may detoxify poisonous lactose-like molecules and increases their export.

Promoter

A DNA regulatory element where transcription factors and RNA polymerase must bind to transcribe the operon.

Operator

A DNA regulatory element where the Lac I Repressor protein must bind to repress transcription.

Lac I Repressor Protein

The regulatory protein that controls Lac operon expression by binding to the operator to prevent RNA polymerase from binding to the promoter.