genetic engineering, the process of producing recombinant DNA for the purposes of altering and controlling the genotype and phenotype of organisms. Restriction enzymes are used to break a DNA molecule into fragments so that genes from another organism can be inserted into the DNA. Genetic engineering has been used to produce a variety of human proteins, including growth hormone, insulin, and interferon, in bacteria. At present, it represents a powerful tool for medical research but is possible only in microorganisms. In the future, genetic engineering may be applicable to more complex organisms, offering the possibility of controlling and eliminating genetic disorders and malformations in humans.