Question

Assertion (A): E. coli having pBR322 with DNA insert at BamHI site cannot grow in medium containing tetracycline.

Reason (R): Recognition site for BamHI is present in tetr region of pBR322.

Options

• Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.

• Both assertion (A) and reason (R) are true, but reason is not the correct explanation of assertion.

• Assertion (A) is true but reason (R) is false.

• Both assertion (A) and reason (R) are false.

Answer 1

Both assertion (A) and reason (R) are true, and reason is the correct explanation of assertion.

Explanation:

The BamHI site lies within the tetracycline-resistance gene of pBR322. Inserting foreign DNA there inactivates that gene, so the recombinant bacteria cannot grow on tetracycline.