DNA replication. Technician with rows of thermocyclers used in research into the human genome at Celera Genomics, Maryland, USA, a rival to the Human Genome Project. Thermocyclers clone DNA using a polymerase chain reaction (PCR). Celera aims to sequence every gene in human DNA (deoxyribonucleic acid) by 2001. Human DNA is made up of some 30,000 genes among over 3 billion base pairs. Celera sequences DNA fragments and uses supercomputers to put the pieces together. This is a cruder but faster method than that used by the publicly-funded Human Genome Project. The complete human genome map will allow improved drug design and a greater understanding of genetic diseases.