Question

Operon is a coordinated group of genes that function together as a unit for a metabolic pathway. How many statements below are correct with respect to lac operon?
i) Glucose or galactose may bind with the repressor and inactivate it.
ii) In the absence of lactose, the repressor binds with the operator region.
iii) The Z-gene codes for permease.
iv) I- gene codes for repressor protein

• A. I and II
• B. II and III
• C. I and III
• D. II and IV

Answer 1

The correct option is D II and IV

The i-gene codes for a repressor protein that binds to the operator in the absence of lactose to prevent the transcription of lac operon.
Lactose is inducer in lac operon and binds with the repressor protein thereby preventing the repressor protein to bind with the operator and transcription can take place.

Z gene found in lac operon is one of the structural gene and codes for ꞵ -galactosidase which digests the lactose into - glucose and galactose.
Whereas it is Y gene that codes for permease enzyme in the lac operon.