DNA autoradiograms. Computer artwork of DNA (deoxyribonucleic acid) autoradiograms or 'genetic fingerprints'. Each sequence is composed of four columns of irregularly spaced bands of DNA. To form an autoradiogram, a DNA sample is taken from body fluids or tissues and is fragmented using enzymes. The fragments are separated under an electric current (electrophoresis) to form the banding patterns seen here. The bands show the position of the base pairs on a DNA molecule. As each person has a unique sequence of base pairs, an autoradiogram of their DNA provides a unique 'genetic fingerprint' which can be used to identify them.