Final answer:
The lac operon in E.coli bacteria consists of a promoter, an operator, and three genes that encode enzymes involved in lactose metabolism. The lacZ gene encodes beta-galactosidase, the lacY gene encodes lactose permease, and the lacA gene encodes transacetylase. The operator is a DNA sequence that regulates gene expression by binding to a repressor protein.
Step-by-step explanation:
The lac operon is a stretch of DNA in E.coli bacteria that consists of a promoter, an operator, and three genes (lacZ, lacY, and lacA) that encode the enzymes needed to digest lactose. The lac operon is regulated by lactose in the environment.
The lacZ gene encodes for the enzyme beta-galactosidase, which converts lactose into glucose and galactose. The lacY gene encodes for the lactose permease protein, which transports lactose into the bacterial cell. The lacA gene encodes for the transacetylase enzyme, which is involved in lactose metabolism.
The operator is a DNA sequence located between the promoter and the structural genes. In the absence of lactose, a protein called the repressor binds to the operator, preventing RNA polymerase from binding to the promoter and transcribing the genes. When lactose is present, lactose or its metabolite allolactose binds to the repressor, causing it to detach from the operator and allowing RNA polymerase to initiate transcription.