THE HUMAN GENOME
The rediscovery of Mendel's laws of heredity in the opening weeks of the 20th century sparked a scientific quest to understand the nature and content of genetic information that has propelled biology for the last hundred years. The scientific progress made falls naturally into four main phases, corresponding roughly to the four quarters of the century.
1º) The first established the cellular basis of heredity: the chromosomes.
2º) The second defined the molecular basis of heredity: the DNA double helix.
3º) The third unlocked the informational basis of heredity, with the discovery of the biological mechanism by which cells read the information contained in genes and with the invention of the recombinant DNA technologies of cloning and sequencing by which scientists can do the same.
4º) The last quarter of a century has been marked by a relentless drive to decipher first genes and then entire genomes, spawning the field of genomics. The fruits of this work already include the genome sequences of 599 viruses and viroids, 205 naturally occurring plasmids, 185 organelles, 31 eubacteria, seven archaea, one fungus, two animals and one plant.
And now, the human being...
The draft genome sequence was generated from a physical map covering more than 96% of the euchromatic part of the human genome and, together with additional sequence in public databases, covering about 94% of the human genome.
The sequence of the human genome is of interest in several respects. It is the largest genome to be extensively sequenced so far, being 25 times as large as any previously sequenced genome and eight times as large as the sum of all such genomes. It is the first vertebrate genome to be extensively sequenced. And, uniquely, it is the genome of our own species.
New data are continually being added (the total amount of finished sequence is now around 1 Gb.), with improvements being made to the physical map, new clones being sequenced to close gaps and draft clones progressing to full shotgun coverage and finishing. The draft genome sequence will be regularly reassembled and publicly released (http://www.nature.com/genomics/human/).