The recombinants lose the resistance to ampicillin if genes are inserted at the following sites of pBR322.
The restriction sites present at the marker are Pvu I and Pst I. If a gene is inserted at one of these sites by using respective endonucleases and ligases, the recombinant looses the resistance to antibiotic ampicillin which is known as insertional inactivation. EcoR I and Cla I are present between the two markers and upon insertion of gene at these sites, the recombinant still retains the resistance to both ampicillin and tetracyclin. Hind III is also present at the non-marker region. BamH I and Sal I are present at the marker region. Pvu II is present at rop region of vector.