NEET2026BiologyChapterActual
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): When a foreign DNA is ligated at the Bam H I site of the cloning vector pBR322, the resulting recombinant transformants will grow on an ampicillin-containing medium but fail to grow on a tetracycline-containing medium. Reason (R): The insertion of the foreign DNA at the Bam H I site causes insertio
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- C(A) is correct but (R) is incorrect
- D(A) is incorrect but (R) is correct
Correct answer
C. (A) is correct but (R) is incorrect
Step-by-step solution
In the cloning vector pBR322, the restriction site for the enzyme Bam H I is located within the tetracycline resistance gene ( tet^R ). When a foreign DNA is ligated at the Bam H I site, it disrupts the tet^R gene, leading to its insertional inactivation. As a result, the recombinant plasmid loses resistance to tetracycline but retains resistance to ampicillin. Therefore, the recombinant transformants will grow on an ampicillin-containing medium but will fail to grow on a tetracycline-containing medium. This makes