Prokaryotic Gene regulation

Operon

A region of DNA consisting of the promoter, operator, and coding sequence of the genes.

Polycistronic mRNA

Prokaryotic mRNA that contains multiple structural genes within it.

Structural Gene

A gene that codes for a protein, necessary for the function of the operon.

lacI

Gene that encodes the repressor protein for the lac operon.

lacO

Operator region where the repressor protein binds, preventing transcription.

lacP

Promoter that recruits RNA Polymerase and initiates transcription of the lac operon.

lacZ

Gene that codes for beta-galactosidase which cleaves lactose.

lacY

Gene that codes for lactose permease, transporting lactose into the cell.

RNA Polymerase

Enzyme that initiates transcription by binding to the promoter.

Repressor Protein

Binds to lacO to halt transcription of the lac operon.

Lactose

Inducer that binds to the repressor, allowing transcription to occur.

CRP-cAMP Binding Site

Site where cAMP binds, enhancing transcription in response to low glucose.

Negative Regulation

Mechanism by which the presence of a repressor protein prevents gene transcription.

Positive Regulation

Mechanism by which CRP-cAMP activates gene expression.

High Glucose/No Lactose

Condition resulting in no transcription of the lac operon.

High Glucose/Low Lactose

Condition leading to low transcription of the lac operon.

Low Glucose/High Lactose

Condition resulting in high transcription of the lac operon.

Low Glucose/Low Lactose

Condition leading to low transcription of the lac operon.