Final answer:
An operon in prokaryotes includes a promoter, an operator which regulates transcription, structural genes coding for related proteins, and regulatory sites for repressors or activators. Mutations in any part of the operon can affect metabolic functions, such as lactose metabolism in the lac operon.
Step-by-step explanation:
The Structure of an Operon
An operon is a fundamental genetic regulatory system found in prokaryotes that consists of four main elements: promoter, operator, structural genes, and regulatory genes or sites. The promoter is a sequence of DNA where RNA polymerase binds to initiate transcription. The operator is positioned near the promoter and acts as a control element for the transcription of the operon genes by allowing or preventing RNA polymerase progression based on the binding of repressors or activators. The structural genes of an operon are transcribed together and code for proteins that participate in a common pathway or process, like lactose metabolism in the case of the lac operon. Lastly, regulatory genes produce proteins such as repressors or activators that bind to the operator or promoter and modulate gene expression. A mutation in any of these components can alter gene expression, exemplified by the lac operon, where a mutation in one of its structural genes could disrupt lactose metabolism.