A group of genes involved in the same function, sharing the same promoter site and operator, is called an operon.

Here's why:

* Operon: An operon is a functional unit of DNA containing a cluster of genes under the control of a single promoter and operator.

* Promoter: This is the DNA sequence where RNA polymerase binds to initiate transcription.

* Operator: This is the DNA sequence where a repressor protein binds to regulate gene expression.

This structure allows for coordinated regulation of the genes within the operon, ensuring that all genes are transcribed and translated together when needed.

Example: The *lac* operon in bacteria contains genes for lactose metabolism. When lactose is present, it binds to the repressor protein, allowing RNA polymerase to transcribe the genes and produce the enzymes needed to break down lactose.