Caption

DNA sequencing. A geneticist examines a computer display of a DNA (deoxyribonucleic acid) sequencing pattern, with the four chemical bases in DNA shown in colour. The bases in DNA are repeated millions of times along the molecule, with their sequence spelling out in code form the entire set of genes (the genome) in an individual. Working out the base- sequence of specific fragments of DNA allows genes to be identified and their function established.