©Wellcome Photo Library

The output from an automated gene sequencer used by the Human Genome Project to determine the complete human DNA sequence. Each vertical lane shows the sequence of bases in a given stretch of DNA. Each of the 4 different bases is labelled with one of the 4 coloured dyes. The order of the bases is analysed by a computer and assembled to give the continuous base sequence of each chromosome. This image shows the sequence of only a tiny part of one chromosome.

Source: The Sanger Centre, Cambridge.