Bio 113 Lecture 14 (Prokaryotic Gene Expression

Operator

in bacterial DNA, a sequence of nucleotides near the start of an operon to which an active repressor can attach. The binding of the repressor prevents RNA polymerase from attaching to the promoter and transcribing the genes of the operon

Operon

a unit of genetic function found in bacteria, consisting of a promoter, an operator, and a coordinately regulated cluster of genes whose production function in a common pathway

Repressor

a protein that inhibits gene transcription. In prokaryotes, repressors bind to the DNA in or near the promoter. In eukaryotes, repressors may bind to control elements within enhancers, to activators, or to other proteins in a way that blocks activators from binding to DNA

Regulatory gene

a gene that codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes

Corepressor

a small molecule that binds to a bacterial repressor protein and changes the protein’s shape, allowing it to bind to the operator and switch an operon off

Inducer

a specific small molecule that binds to a bacterial repressor protein and changes the repressor’s shape so that it cannot bind to an operator, thus switching an operon on

Cyclic AMP (cAMP)

cyclic adenosine monophosphate, named because of its ring structure, is a common chemical signal that has a diversity of roles, including as a second messenger in many eukaryotic cells, and as a regulator of some bacterial operons

Activator

a protein that binds to DNA and stimulates gene transcription. In prokaryotes, activators bind in or near the promoter; in eukaryotes, activators generally bind to control elements in enhancers