Molecular Basis of Inheritance Question 122
122. Which of the following is required as inducer(s) for the expression of Lac operon?
(a) Glucose
(b) Galactose
(c) Lactose
(d) Lactose and galactose
Show Answer
Answer : c
Hints & Solution
(c) Lac operon is an inducible operon. Lactose is the substrate for the enzyme beta-galactosidase and it also regulates switching on and off of the operon. Hence, it is termed as inducer. Inducer functions by disabling repressors. The gene is expressed because an inducer binds to the repressor. The binding of the inducer to the repressor prevents the repressor from binding to the operator. RNA polymerase can then begin to transcribe structural genes.
