Components of lac operon

Inducer-repressor complex

A molecular complex consisting of repressor protein and a bound inducer molecule

Operon

A set of adjacent genes that are transcribed in a polycistronic mRNA and thus are coordinately regulated

Activator protein

A transcription factor that binds to regulatory sequences associated with a gene

Inducer

Accessory molecule that binds to a protein that leads to the activation of gene expression; can bind to a repressor protein and prevent its function or to an activator protein and stimulate its function

Lac operon

An inducible operon system under both negative and positive control

Polycistronic

Describes a type of mRNA that can encode for more than one polypeptide separately within the same RNA molecule

Attenuation

Fine tuning of the rate of transcription in response to the needs of the cell

CAP-cAMP complex

Formed by joining CAP to cAMP; the complex binds to the CAP binding site of the bacterial lac promoter to regulate gene expression

Transcription factor

Protein that binds promoters and is functional in transcription

Promoter

Regulatory DNA sequence near 5' end of a gene that acts as the binding site for RNA polymerase and directs RNA polymerase to the start of transcription

Operator

Regulatory DNA sequence that a repressor or activator binds to

Anabolic pathway

Synthesizes a needed compound

RNA polymerase

The enzyme that catalyzes the synthesis of RNA

Repressor protein

Transcription factor that binds to regulatory sequences associated with a gene and represses that gene's expression

CAP binding site

Where positive control of lac operon occurs