Question

In the Lac operon, the repressor protein exerts a negative effect on the expression of structural genes in the absence of inducer molecule. In case of the Lac operon, what is the inducer molecule?

• A. Allolactose
• B. Glucose
• C. RNA polymerase
• D. Galactose

Answer 1

The correct option is A Allolactose

• Glucose is the usual source of energy for the cell and prevents the expression of the structural gene of Lac operon.
  
• Although lactose ultimately turns on the expression of the lac operon, it does not directly regulate the transcription of operon.
  
• Allolactose, a metabolite of lactose, is the inducer molecule in Lac operon.