Operon
An operon is a group of genes including an operator, a common promoter, and one or more structural genes that are controlled as a unit to produce messenger RNA (mRNA). Operons occur primarily in prokaryotes and nematodes.
They were first described by François Jacob and Jacques Monod in 1961.
The operon as a unit of transcription An operon is a unit of transcription consisting of one or more structural genes, and two associated segments of DNA: an operator (the switch) a promoter (a binding site for the transcription enzyme). The switch of an operon (that is, the "operator") is turned on unless a specific substance is bound to the operator. This substance is therefore called a repressor. In summary: The "operator" is a DNA binding site for a repressor; transcription of the structural genes takes place unless a repressor is bound to the operator.
See also gene regulatory networkLac operon
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