Repressible Operon

A repressible operon is a group of genes in bacteria that are usually active but can be shut down when the cell produces enough of a specific substance. When the substance is abundant, it binds to a repressor protein, activating it. The repressor then attaches to the DNA, blocking gene activity and stopping production of that substance. This mechanism helps bacteria conserve resources. An example is the tryptophan operon, which switches off when enough tryptophan, an amino acid, is available, ensuring efficient regulation of gene expression based on cellular needs.