NEETZoologyBiotechnology - Principles and Processes
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Recombinant E. coli produced after inserting foreign DNA at the Pst I site of pBR322 will grow on a medium containing tetracycline but not on a medium containing ampicillin. Reason (R): The Pst I restriction site is located within the ampicillin resistance gene, and insertion of foreign DNA here le
Options
- ABoth Assertion and Reason are true and Reason is the correct explanation of Assertion.
- BBoth Assertion and Reason are true but Reason is not the correct explanation of Assertion.
- CAssertion is true but Reason is false.
- DAssertion is false but Reason is true.
Correct answer
A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Step-by-step solution
In the cloning vector pBR322, the restriction sites Pst I and Pvu I are located within the ampicillin resistance gene ( amp^ R ). When foreign DNA is inserted at the Pst I site, the amp^ R gene undergoes insertional inactivation. As a result, the recombinant plasmid loses the ability to confer resistance to ampicillin, while retaining resistance to tetracycline (since the tet^ R gene remains intact). Thus, the recombinant E. coli transformants will grow on a medium containing tetracycline but will fail to grow on a