Genetic engineering is the term applied to techniques that alter the genes (hereditary material) or combination of genes in an organism. The cells of all living organisms contain genes. Genes carry chemical information that determines the organism's characteristics. By changing an organism's genes, scientists can give the organism and its descendants different traits. Researchers have found important uses for genetic engineering in such fields as medicine, industry, and agriculture. Many new uses are predicted for the future.

A number of human illnesses are caused by the failure of certain genes in the body to make specific proteins. For example, the failure of genes in the pancreas to make insulin causes diabetes. Scientists can produce large quantities of insulin in bacterial "factories" by splicing the insulin gene isolated from human cells to plasmids from cells of Escherichia coli bacteria. The insulin is then given to patients who need it. Researchers also have engineered E. coli to make proteins called interferons, which are normally produced by body cells in response to viral infections. They have been tested against many diseases.

Scientists have developed numerous genetically engineered plants. Special genes have been engineered into tomato plants to enable them to produce tomatoes with increased flavor and shelf life. Small plants have been genetically engineered to produced small amounts of a biodegradable plastic. Such crops as cotton, corn, soybeans, papaya, and squash have been engineered to resist disease or injury from herbicides, insects, or viruses.

Excerpt from the "Genetic engineering" article, The World Book Encyclopedia © 1999