With the advent of genetic engineering, scientists are now able to surpass the natural barriers of cross-breeding. Genetic engineers can cut out bits of a living organism's DNA, called genes, and splice them into totally unrelated species. Genetic engineering changes nature rather than using its own power. Genes carry messages encoded in their chemical structure, so that together the genetic make-up of a living cell determines physical traits of that organism. The genes carry all the chemical instructions needed to make the organism behave in a certain way, and since they are passed on from one generation to the next, offspring inherit these traits from their parents.
Genes are complex and work together to perform certain biological functions.
By altering the genetic code of living organisms, genetic engineers are manipulating life processes. As more and more genes are isolated from their natural sources, scientists are able to control more and more aspects of life. The majority of the world's most important food crops have already been either tested for genetically engineered versions, or are under development. So far at least 38 different crop species have been genetically engineered and tested in field trials. Animal genes are going into plants, bacteria genes into food crops, and even human genes are being used to change animals and plants.