Question

What is the function of red and gam gene products?

(a) It promotes the growth of the phage in the E. coli cells which are lysogenic for bacteriophage P1

(b) It inhibits the growth of the phage in the E. coli cells which are lysogenic for bacteriophage P2

(c) It inhibits the growth of the phage in the E. coli cells which are lytic for bacteriophage  P1

(d) It activates the growth of the phage in the E. coli cells which are lytic for bacteriophage P2

This question was posed to me in a job interview.

Question is taken from Cloning in Lambda topic in chapter Other Vector Systems for E of Genetic Engineering

Answer 1

Right choice is (b) It inhibits the growth of the phage in the E. coli cells which are lysogenic for bacteriophage P2

Easy explanation: The red and gam gene products inhibit the growth of the phage in the E.coli cells which are lysogenic for bacteriophage P2. When red and gam gene products are absent, the growth takes place in the cells which are lysogenic to bacteriophage P2.