Research on the human genome: Caltech scientist Leroy Hood preparing an electrophoresis gel used in a computer-controlled system for DNA sequencing of human chromosomes. DNA sequencing involves decoding the base pair sequence of sections of DNA encode specific proteins. Sequencing and mapping chromosomes to locate genes or other important markers - are two phases in the human genome project. The human genome is a complete genetic blueprint - a detailed plan of every gene expressed on all 23 pairs of chromosomes. MODEL RELEASED (1989).