Plasmid pBR322 has Pst I restriction enzyme site within gene ampR that confers ampicillin resistance. If this enzyme is used for inserting a gene for -galactosidase production and the recombinant plasmid is inserted in an E. coli strain
- It will be able to produce a novel protein with dual ability
- It will not be able to confer ampicillin resistance to the host cell
- The transformed cells will have the ability to resist ampicillin as well as produce -galactosidase
- It will lead to lysis of host cell
Answer
(2) It will not be able to confer ampicillin resistance to the host cell
Solution
The Pst I site lies inside the ampicillin resistance gene (ampR) of pBR322.
⇒ Insertion of the foreign gene at this site disrupts the ampR gene (insertional inactivation).
⇒ The recombinant plasmid can no longer make the protein that gives ampicillin resistance.
∴ The transformed E. coli cells will not be able to resist ampicillin (they still resist tetracycline through tetR).
No fused protein is formed and the host cell is not lysed.
Answer: (2)