Final answer:
An operon is a cluster of genes in prokaryotes that are transcribed together for a specific function, such as the synthesis of tryptophan or lactose metabolism.
Step-by-step explanation:
Proteins that are needed for a specific function or that are part of the same biochemical pathway in prokaryotes are generally encoded together in a structure known as an operon. An operon is a cluster of genes transcribed as a single mRNA molecule, ensuring that all genes are expressed or repressed together, optimizing the cell's response to environmental changes.
Examples include the trp operon, which is involved in the synthesis of the amino acid tryptophan in bacteria like E. coli, and the lac operon, which contains genes necessary for the metabolism of lactose.