Uses of genetic engineering. Concerns about genetic engineering. 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. For thousands of years, breeders of plants and animals have used breeding methods to produce favorable combinations of genes. Beginning in the 1970's, scientists developed ways to reintroduce individual genes into cells or into plants, animals, or other organisms. Such techniques alter the heredity of the cells or organisms. How genes are reintroduced into cells.