Q. The blue and white selectable markers have been developed which differentiate recombinant colonies from non-recombinant colonies on the basis of their ability to produce colour in the presence of a chromogenic substrate. Given below are two statements about this method: Statement I: The blue coloured colonies have DNA insert in the plasmid and they are identified as recombinant colonies. Statement II: The colonies without blue colour have DNA insert in the plasmid and are identified as recombinant colonies. In the light of the above statements, choose the most appropriate answer from the options given below:
A) Both Statement I and Statement II are correct
B) Both Statement I and Statement II are incorrect
C) Statement I is correct but Statement II is incorrect
D) Statement I is incorrect but Statement II is correct
Explanation
[Solution by Claude - not from source] Insertional inactivation of $\beta$-galactosidase gives white colonies for recombinants; non-recombinants are blue. Statement I is incorrect and II is correct. Answer (4), as in the answer key.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.