The given figure is the diagrammatic representation of the vector pBR322.Which one of the following option correctly identifies its components ?

amp^R ,tet^{R  _} antibiotic resistance genes .  

The correct answer is Option (4) –amp^R ,tet^{R  _} antibiotic resistance genes . 

pBR322 is indeed one of the first artificial cloning vectors developed in 1977 by Boliver and Rodriguez. It is a plasmid derived from Escherichia coli (E. coli) and has been widely used in genetic engineering experiments.

E. coli cloning vector pBR322 showing restriction sites (Hind III, EcoR I, BamH I, Sal I, Pvu II, Pst I, Cla I), ori and antibiotic resistance genes (amp^R and tet^R). rop codes for the proteins involved in the replication of the plasmid.

• amp^R: Confers resistance to ampicillin, allowing the selection of bacteria that have taken up the plasmid.
• tet^R: Confers resistance to tetracycline, providing an additional selection marker.

The other options are incorrect because:

• Ori: This refers to the origin of replication, not "original restriction enzymes."
• Rop: rop codes for the proteins involved in the replication of the plasmid not related to "reduced osmotic pressure."
• Hind III, Eco RI: These are restriction enzymes used for cutting DNA, not selectable markers.

Thus, amp^R and tet^R are the antibiotic resistance genes in the pBR322 vector.