What are genes? They are the basic hereditary units of all living things. Genes are composed of two long complex chains of four basic chemicals would together like a flexible ladder twisted around its long axis. The genetic information in this chain is specified by the order of the four chemicals within the chain. How do genes work? Each gene has two parts: a switch in the front of the gene, which tells it when to turn on or off, and a coding part, which carries the genetic blueprint for the product of the gene.
How do scientists manipulate the genes? They introduce small segments of foreign chemicals into the hereditary makeup fo the organism so that it takes on new characteristics. By using this engineering, scientists can move genes between organisms that could not normally be mated or crossed.