Bolivar and Rodriguez inserted genes for antibiotic resistance in a plasmid from E.coli to form a new plasmid called pBR 322. pBR322 is one of the standard cloning vectors widely used in gene cloning experiments. pBR322 has the following regions ori: Region for origin for replication. rop: This region codes for the proteins involved in the replication of plasmid. This region also has recognition sequence for restriction endonuclease Pvu II (Proteus vulgaris). tetR - This region provides resistance against the antibiotic tetracycline. This region also has recognition sequence for restriction endonucleases: Bam H I from Bacillus amyloliquefaciens and Sal I from Streptomyces albus. ampR - This region provides resistance against the antibiotic ampicillin. This region also has recognition sequence for restriction endonucleases: Pvu I from Proteus vulgaris and Pst I from Providencia stuarti. Apart from these, pBR 322 also shows recognition sequence for restriction endonucleases: EcoR I (its recognition site is 5' GAATTC 3') from Escherichia coli, Hind III from Haemophilus influenza and Cla I from Caryophanon latum.