lyze the production of virtually every other building block of life. Some genes are regulatory and are involved in controlling the activity of other genes. The environmental and chemical sensing mechanisms that regulate gene activity are extraordinarily complex and are the target of a great deal of research.
The fundamental principles used today to sequence DNA were developed in the middle 1970s. The speed with which sequencing can be carried out has increased exponentially and has been largely driven by the development of automated sequencing machines and new technologies. The per-nucleotide cost of sequencing has similarly decreased; it fell by about 2 orders of magnitude between 1998 and 2003 and reached about 2 cents per nucleotide by early 2004. The increase in speed and decrease in cost are expected to continue in much the same way that the power and cost of computer processing chips have changed over the years (Carlson, 2003) (see Figure 1). Indeed, the power of sequencing technology is now