Question

Select the restriction endonuclease enzymes whose restriction sites are present for the tetracycline resistance (tetR) gene in the pBR322 cloning vector

• A. Bam HI and Sal I
• B. Sal I and Pst I
• C. Pst I and Pvu I
• D. Pvu I and Bam HI

Answer 1

Answer: (A)

Bam HI and Sal I

Answer 2

The pBR322 plasmid contains the tetracycline resistance ($\text{tet}^+$) gene. The restriction sites for Bam HI and Sal I are located within the $\text{tet}^+$ gene. Cutting the plasmid with either of these enzymes will disrupt the $\text{tet}^+$ gene, allowing for the selection of recombinant plasmids (those that have taken up a foreign DNA insert).