The massive interest and commitment of resources in both the public and private sectors flows from the generally-held perception that genomics will be the single most fruitful approach to the acquisition of new information in basic and applied biology in the next several decades. If genomics were only to be a tool for the basic biologist, the benefits of this approach would be staggering, yielding new insights into fundamental processes such as cell division, differentiation, transformation, the development and reproduction of organisms and the diversity of populations. The rewards in applied biology, however, have clearly attracted the private sector and public interest. Genomics is operationally defined as investigations into the structure and function of very large numbers of genes undertaken in a simultaneous fashion. Genomics is operationally defined as investigations into the structure and function of very large numbers of genes undertaken in a simultaneous fashion.
Structural genomics includes the genetic mapping, physical mapping and sequencing of entire genomes.
At the present time, perhaps 16 microbial genomes have been sequenced, and the sequences of the human genome and the model organisms listed above are either complete and published or anticipated within the next 2 years. First, the vast numbers of species and the much larger size of some genomes makes the entire sequencing of all genomes a non-optimal approach for understanding genome structure. Second, within a given species most individuals are genetically distinct in a number of ways. The genomes of two individuals who are genetically distinct differ with respect to DNA sequence by definition. These two problems, and the potential for other novel applications, have given rise to new approaches which, taken together, constitute the field of comparative genomics.