Plasmid pBR322 has PstI restriction enzyme site within gene ampR that confers ampicillin resistance. If this enzyme is used for inserting a gene for β-galactoside production and the recombinant plasmid is inserted in an E.coli strain (1) it will not be able to confer ampicillin resistance to the host cell. (2) the transformed cells will have the ability to resist ampicillin as well as produce β-galactoside. (3) it will lead to lysis of host cell. (4) it will be able to produce a novel protein with dual ability.
Option 1) Since the gene is inserted at Pst I of ampR region of pBR322, the ampR gene is inactivated which is called as insertional inactivation. Hence the genetically modified E.coli strain will not be able to confer ampicillin resistance.
