A genetic engineer is attempting to introduce a human gene into the plasmid vector pBR322. If the human DNA fragment was isolated by digesting the human genome with the restriction enzyme BamH I, which of the following enzymes must be used to cleave the pBR322 plasmid to ensure successful ligation?

Step-by-step solution

For a recombinant DNA molecule to be created, both the source DNA (human gene) and the vector DNA (pBR322) must be cut with the same restriction endonuclease. Using the same restriction enzyme ensures that both DNA molecules have complementary sticky ends, which can then be joined by the enzyme DNA ligase. Since the human DNA was cut with BamH I, the pBR322 plasmid must also be cut with BamH I. Using any other enzyme (like EcoR I, Sal I, or Hind III) would generate incompatible ends that cannot be ligated. Answer: