The genome is the ultimate source of information about an organism. Advances in genetic engineering techniques made it possible for the scientists to isolate and clone DNA pieces and determine nucleotide sequences of these genome. After the development of practical DNA sequencing methods, serious discussions began about the prospects for sequencing the entire 3 billion base pairs of the human genome. The international Human Genome Project got underway with extensive funding in the late 1980s. The effort eventually included significant contributions from 20 sequencing centers distributed among six nations: the United States, Great Britain, Japan, France, China, and Germany. General coordination was provided by the Office of Genome Research at the National Institutes of Health, led first by James Watson and after 1992 by Francis Collins.
At the outset, the task of sequencing a 3 X 109 bp genome seemed to be a massive job, but it gradually yielded to advances in technology. The completed sequence of the human genome was published in April 2003, several years ahead of schedule. The sequence of chromosome 1 was completed only in May 2006. The Human Genome Project (HGP) was a 13-year project coordinated by the U.S. Department of Energy and National Institute of Health. Decades-old estimates that humans possessed about 100,000 genes within the approximately 3 X 109 bp in the human genome have been supplanted by the discovery that we have only 30,000 to 35,000 genes.
The Human Genome Project marks the culmination of twentieth-century biology and promises a vastly changed scientific landscape for the new century. The human genome is only part of the story, as the genomes of many other species are also being sequenced, including the yeasts Saccharomyces cerevisiae (completed in 1996) and Schizosaccharomyces pombe (2002), the nematode Caenorhabditis elegans (1998), the fruit fly Drosophila melanogaster (2000), the plant Arabidopsis thaliana (2000), the mouse Mus musculus (2002), zebrafish, and dozens of bacterial and archaebacterial species.