Assertion: Insertion of recombinant DNA within the coding sequence of β-galactosidase results in colourless colonies.
Reason: Presence of insert results in inactivation of enzyme β-galactosidase known as insertional inactivation.
(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
(c) If Assertion is correct but Reason is incorrect.
(d) If both the Assertion and Reason are incorrect.
(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
Explanation:
Alternative markers have been developed that can differentiate recombinants from non-recombinants based upon their ability to produce colour in presence of a chromogenic substrate. The plasmid in the bacteria, lacking an insert produces blue coloured colonies, while those plasmids with an insert do not produce any colour due to insertional inactivation of the enzyme, β-galactosidase.