Question

Which of the following is true for an operon?

• A. They are absent in prokaryotes
• B. It consists of a promoter, operator and structural genes
• C. A sequence of three nitrogen bases determining a single amino acid
• D. Gene responsible for switching on and switching off of other genes

Answer 1

The correct option is B It consists of a promoter, operator and structural genes

Operons generally occur in prokaryotes. An operon is a part of the genetic material (or DNA) which is a co-ordinated group of genes that act as a single regulatory unit having one or more structural genes, an operator gene and a promoter gene. The operon is usually regulated by a regulatory gene which codes for the repressor protein, which, in turn, plays a major role in switching the operon on and off.