Question

Identify the labels A, B, C and D in the given diagram

• A. A: EcoR I, B: BamH I, C: Ori, D: Ampicillin resistance gene
• B. A: BamH I, B: EcoR I, C: Ampicillin resistance gene, D: Ori
• C. A: origin of replication, B: Hind II, C: BamH I, D: amp^R
• D. A: EcoR I, B: Hind II, C: Ori, D: amp^R

Answer 1

The correct option is A A: EcoR I, B: BamH I, C: Ori, D: Ampicillin resistance gene

The diagram in the question depicts the plasmid pBR322 which is an artificial cloning vector constructed by Bolivar and Rodriguez.

The features of the plasmid are:

- It has an ori site. It is the site at which replication begins.

- It has a rop region. The rop codes for the proteins involved in the replication of the plasmid.

- It has two antibiotic resistance genes that act as selectable markers.
Ampicillin resistance gene: amp^R and tetracycline resistance gene: tet^R

- Restriction sites are specific DNA sequences within which restriction endonucleases (restriction enzymes) cleave phosphodiester bonds and create DNA fragments.

pBR322 has restriction sites for the following restriction enzymes - Pst I, Pvu I, EcoR I, Cla I , Hind III, BamH I, Sal I and Pvu II.

Hence, A: EcoR I , B: BamH I, C: Ori, D: Ampicillin resistance gene (amp^R)