Gene manipulation involves externally arranging genes within an organism and is also known as genetic engineering. It was first used in agriculture to improve plant quality and was discovered in native Mexican corn in 2001. The process involves isolating DNA from an organism, introducing it into a vector or plasmid using restriction enzymes, and transforming it into a host cell. Restriction enzymes recognize specific DNA sequences and cleave the phosphodiester bonds between nucleotides at that site in viral, frog, or human DNA. Gene manipulation is concluded to include gene splicing, using recombinant DNA, forming monoclonal antibodies, and employing PCR thermocyclers, though it is not allowed for genetic manipulation in humans.