Chemically synthesized DNA sequences for the two chains are separately inserted into the plasmid pBR 322 by the side of

pBR322 plasmid is a commonly used plasmid cloning vector in E. coli bacteria. Since PvuI restriction site is present in ampicillin resistant gene, when we ligate a foreign DNA at PvuI site, the ampicillin resistant gene gets destroyed. The recombinant plasmid thus formed will lose the resistance to the ampicillin.