Question

Plasmid pBR322 has a Pst l restriction enzyme site within gene amp^R 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:

• A. It will lead to lysis of the host cell
• B. It will not be able to confer ampicillin resistance to the host cell
• C. It will be able to produce a novel protein with a dual ability
• D. The transformed cells will have the ability to resist ampicillin as well as produce β-galactoside

Answer 1

The correct option is B

It will not be able to confer ampicillin resistance to the host cell

The correct option is B

Explanation of the correct option:

1. Due to the insertion of the gene at Pst I of amp^R region of pBR322, the amp^R gene is inactivated.
2. This is called insertional activation.
3. As a result, ampicillin resistance would not be conferred.

Explanation of the incorrect options:

Option A:

1. Lysis is the reproduction of viruses using a host cell.
2. It is not a result of insertional inactivation.

Option C:

1. The insertion of the gene does not produce a novel protein with dual ability.
2. It only hinders ampicillin resistance.

Option D:

1. The transformed cells will not have the ability to resist ampicillin as well as produce β-galactoside.
2. This is because the gene had been inactivated before the transformation.

Final answer: Plasmid pBR322 has a Pst l restriction enzyme site within gene amp^R 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, it will not be able to confer ampicillin resistance to the host cell.