Assertion : The insertion of DNA fragment into pBR 322 plasmid using enzyme Pst I or Pvu I make ampicillin resistant gene non functional.
Reason : Bacterial cells containing recombinant pBR322 is unable to grow in the presence of ampicillin.
Answer (b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(b) : Plasmid pBR322 has a variety of unique restriction sites for restriction endonucleases. Two unique sites, Pst I and Pvu I are located within the ampr gene and BamHI, Sal I etc. are within tetr gene. The presence of restriction sites within the marker tetr and ampr permits an easy selection for cell transformed with the recombinant pBR322. Insertion of the DNA fragment into the plasmid using enzyme Pst I and Pvu I places the DNA insert within the gene ampr and make it non functional.
