The Lac Operon is an example of an inducible system of gene expression. Its default state is to be inactive. Only when the right catalyst is added to the system, in this case the sugar lactose, is the process activated, allowing the genes in question to be expressed.

FIRST LOOK		ADVANCED LOOK		FLASH
An overview of the lac operon system and its key components.		An in-depth look at the major players and events that control the lac operon system.		An embedded Flash movie version of the lac operon animation.