The Human Genome Project set out to determine the base pairs that make up human DNA.
Launched in 1990, the international project aimed to map and sequence the human genome—the complete genetic instruction set carried in human cells. DNA is the molecule that stores this hereditary information, using four bases: adenine, thymine, cytosine and guanine. Their order forms the sequence researchers wanted to read.
The project did not sequence a single person’s entire genetic identity. Scientists assembled a reference sequence from DNA samples contributed by several individuals, representing the 23 pairs of human chromosomes. The public project announced completion in 2003, although difficult repetitive regions remained unresolved.
A common mix-up is confusing DNA sequencing with RNA sequencing or protein analysis. RNA and proteins are important products or expressions of genetic information, but the HGP’s central target was DNA itself. Later work, including telomere-to-telomere projects, filled many gaps left by the original effort.