Caption

DNA research. View of the tip of a pipettor (upper left), a type of automatic pipette, and microtubes in a rack on top of a DNA sequence. The DNA sequence, which is also known as an autoradiogram, is four rows of irregularly spaced black bands. A DNA sample can be taken from body fluids and tissues. The DNA is then fragmented with enzymes and arrayed by size by electrophoresis (separation under an electric field). The banding pattern is then exposed onto an X-ray film. The bands represent the positioning of the base pairs (cytosine-guanine and adenine- thymine) on the DNA chain. This makes up the genetic code which is unique to every person.