genetic engineering
techniques by which the genetic contents of living cells or viruses can be deliberately altered, either by modifying the existing genes or by introducing novel material (e.g., a gene from another species). Genetic engineering is undertaken for many different reasons, including basic research on genetic mechanisms, the large-scale production of particular gene products (e.g., medically useful proteins), and the genetic modification of crop plants. There have also been attempts to modify defective human body cells in the hope of treating certain genetic diseases. There remains, however, considerable public concern about the risks and limits of genetic engineering in plants and animals, including humans. See also gene splicing; recombinant DNA.