During the past 50 years, biology has been transformed by the application of chemical knowledge and methodology. In this chapter we first examine our understanding of how genetic information is transmitted and used. We begin with an introduction to the molecular basis of heredity — deoxyribonucleic acid (DNA) and its component chemical parts. These parts — four nitrogen-containing bases, a sugar (deoxyribose), and phosphate group — are combined into a double helix. That structure and the story of its remarkable discovery are recounted next. Thanks to superb chemical cryptographers, DNA has been decoded. Indeed, the entire molecular code for humans recently has been described for the first time. The genetic code directs the synthesis of proteins and determines the sequence of their constituent amino acids in all living organisms.

The remainder of the chapter addresses some of the many applications of genetic engineering. First you will encounter the recombinant DNA techniques that have made it possible to use bacteria to produce proteins such as human insulin and growth hormones. A whole generation of new drugs and vaccines has also been created through molecular manipulation. New methods of diagnosing diseases are presented next, followed by a discussion of gene therapy, in which normal genes are introduced into patients lacking them. It is now possible to take a unique genetic fingerprint of any one of us. Such information is valuable in solving crimes, identifying human remains, and constructing genetic family trees. Some very old DNA has already been isolated and studied, raising the possibility of a Dino-Disneyland. Some unusual inter-species genetic combinations also surface and are the basis for introducing important new characteristics into agricultural products like StarLink corn. The transfer of genetic material from one species to another gives rise to the "Frankenfood frenzy." We visit the technology that made the cloning of a sheep named Dolly several years ago and issues pertaining to that achievement. Then we devote some attention to the recently-completed, massive project to map all the genes in the human species. The chapter ends with a hope and a warning as we look to a future filled with the benefits and risks of cloning and genetic engineering.