Question

Which of the following is a plasmid?

• A. pBR 322
• B. Bam H I
• C. Sal I
• D. Eco R I

Answer 1

The correct option is A pBR 322

Plasmid vectors are extra-chromosomal, self-replicating, usually circular, double-stranded DNA molecules, found naturally in many bacteria and also in some yeast. pBR322 vector was the first artificial cloning vector constructed in 1977 by Boliver and Rodriguez. It is widely used in gene cloning experiments.
Nomenclature : In pBR 322 plasmid p- denotes that it is a plasmid; BR – strands for Bolivar and Rodriguez who constructed this plasmid; 322- is a number given to distinguish this plasmid from others developed in the same laboratory.