An operon is a sequence of DNA containing a cluster of genes under the control of a single promoter
- Hence, genes within an operon will always be expressed together or not at all (their expression patterns are linked)
There are three basic components to an operon
- Promoter – Upstream sequence to which RNA polymerase binds
- Operator – Segment of DNA to which a repressor protein binds (inhibits transcription by obstructing RNA polymerase)
- Structural genes – Genes that are collectively regulated by the operon
Operons are related to stimulons and regulons:
- Stimulon – Set of genes under regulation from a single cell stimulus
- Regulon – Set of genes under regulation from a single regulatory protein (each gene has a different operator though)
Originally, operons were thought to exist only in prokaryotes, however examples have since been found in eukaryotes
Structure of an Operon
