Editing Operon (section)

== The ''lac'' operon ==

{{Main|lac operon}}

The ''lac'' operon of the [[model organism|model]] bacterium ''[[Escherichia coli]]'' was the first operon to be discovered and provides a typical example of operon function. It consists of three adjacent [[structural gene]]s, a [[promoter (biology)|promoter]], a [[Terminator (genetics)|terminator]], and an [[operator (biology)|operator]]. The ''lac'' operon is regulated by several factors including the availability of [[glucose]] and [[lactose]]. It can be activated by [[allolactose]]. Lactose binds to the repressor protein and prevents it from repressing gene transcription. This is an example of the [[derepression|derepressible]] (from above: negative inducible) model. So it is a negative inducible operon induced by presence of lactose or allolactose.