pBR322 is an E. coli plasmid vector bearing two antibiotic resistance genes: tetracycline and ampicillin. The conventional numbering of nucleotides begins with the first T in the unique EcoRI site and the numbering continues through the tetracycline gene. The peptide coding region of the tetracycline resistance gene ranges from nucleotide 86 to 1276 and the ampicillin resistance gene ranges from nucleotide 3293 to 4153. pBR322 is a circular double stranded DNA containing 4361 base pairs and having a molecular weight of 2.88X10e6 daltons.
