The regulation of gene expression Gene regulation is the process of controlling which genes in a cell’s DNA are expressed (used to make a functional product such as a protein). The lac operon • The lac operon of E. coli contains genes involved in lactose metabolism. It’s expressed only when lactose is present and glucose is absent. • Two regulators turn the operon “on” and “off” in response to lactose and glucose levels: the lac repressor and […]