Question

The regulation of the lac operon is referred as negative regulation because:

• A. the regulatory molecule stops the transcription of structural genes
• B. it gets activated only in the presence of lactose
• C. the products of the structural genes digest lactose
• D. All the above statements are correct

Answer 1

The correct option is A the regulatory molecule stops the transcription of structural genes

The inhibitor/ regulator gene in lac operon codes for a repressor protein which binds with the operator gene and restricts the transcription of structural genes. Repressor proteins have an inhibiting property whose absence and presence controls the switching on and off of the operon respectively. Thus, lac operon is an example of negative regulation.