Question

In prokaryotic but not eukaryotic cells, a ______ precedes the genes of an operon.

Options

• lactose molecule

• promoter

• operator

• both promoter and operator

Answer 1

In prokaryotic but not eukaryotic cells, a promoter and operator precede the genes of an operon.

Explanation:

In prokaryotes, an operon is a functional unit of DNA where multiple related genes are controlled by a single promoter and an operator. While eukaryotes have promoters, they generally do not organise their genes into operons controlled by a single operator. Therefore, both the specific arrangement of a promoter preceding a cluster of genes and the presence of an operator are characteristic features found in prokaryotic operons but not in the individual gene expression systems of eukaryotes.