Gel electrophoresis is used to test for genes related to specific illnesses, to identify DNA associated with crime scenes, to discover paternity and to track evolutionary relationships. This technique is important in medical, biological and criminal science.
To perform gel electrophoresis, a scientist places a solution of DNA molecules in a gel matrix of agarose. DNA has an electric charge, making it possible to pull the genetic material through the gel using an electric field. The small molecules move faster than the large ones, which creates the characteristic banded pattern that scientists compare with other patterns to determine similarity or difference. Viewers of "CSI," "Law & Order" and other detective shows are familiar with these charts, for they are often depicted as important pieces of evidence in such crime dramas.