Question

Read the given statements and select the correct option.
Statement-1: In insertional inactivation, blue colour produced by bacterial colonies indicates that the plasmid does not have an insert into the bacterial genome.
Statement-2: Presence of insert results into insertional inactivation of beta- galactosidase enzyme and the colonies do not produce any colour.

• A. Both statements 1 and 2 are correct and statement 2 is correct explanation of statement 1
• B. Both statements 1 and 2 are correct but statement 2 is not correct explanation of statement 1
• C. Statement 1 is correct and statement 2 is incorrect
• D. Both statements 1 and 2 are incorrect

Answer 1

The correct option is A Both statements 1 and 2 are correct and statement 2 is correct explanation of statement 1

In the insertion inactivation process, a recombinant DNA is inserted within the coding sequence of an enzyme, beta- galactosidase. This results into inactivation of the enzyme, which is referred to as insertional inactivation. The presence of a chromogenic substrate gives blue coloured colonies if the plasmid in the bacteria does not have an insert. Presence of insert results into insertional inactivation of the beta-galactosidase and the colonies do not produce any colour which are identified as recombinant colonies.