Class 12 NEET Biology Biotechnology Principles and Processes Part 2

Concept:The pBR322 vector is a commonly used plasmid in genetic engineering with two antibiotic resistance genes: ampicillin resistance (amp⁺) and tetracycline resistance (tet⁺). Each gene has specific restriction sites where foreign DNA can be inserted.Key Fact:The BamHI restriction site in pBR322 is located within the tetracycline resistance gene.Explanation:When a foreign DNA fragment is inserted at the BamHI site, it disrupts the coding sequence of the tetracycline resistance gene.This disruption prevents the production of the functional protein needed for tetracycline resistance.As a result, the recombinant plasmid loses its ability to confer resistance to tetracycline.The ampicillin resistance gene remains intact because its restriction sites (e.g., PvuI, PstI) are different from BamHI.Answer:Tetracycline