Lac Operon

The Lac Operon is a classic example of a regulatory system found in bacteria, specifically E. coli, that controls the expression of genes involved in lactose metabolism. It consists of a set of genes, including lacZ, lacY, and lacA, which encode proteins responsible for breaking down lactose into its constituent sugars, glucose, and galactose. The operon is regulated by a repressor protein, LacI, which binds to the operator region of the operon and prevents transcription of the genes in the absence of lactose. When lactose is present, it binds to the repressor protein, causing a conformational change that releases the repressor from the operator and allows transcription to occur. This system allows bacteria to use lactose as an energy source only when it is available, conserving energy when other sources are present.