Molecular geneticist loading samples onto an automated DNA sequencer.
© Science Museum / Science & Society Picture Library
Photograph taken at Great Ormond Street Hospital, London, May 2000. Increasingly, scientists are using machines to help them read DNA code. To read a genetic code, DNA fragments are tagged with fluorescent dyes: a different colour for each DNA letter. The fastest machines pull the different sized fragments through a very fine tube, or capillary. A laser beam then detects the moving, fluorescing DNA fragments as they pas.