English: This is a diagram that illustrates the process of Gel electrophoresis. Gel electrophoresis is used for DNA fingerprinting, and is very useful in crime investigation since every individual has different DNA patterns. DNA can be extracted from any sample of body fluid(i.e. blood, semen, or saliva). DNA is mixed with restriction enzyme and amplified with PCR. The mixture of DNA fragment plus restriction enzyme is added into the wells of the agarose gel, which leads to a physical change instead of a chemical one. An electric current is applied to the gel from a power source. Negatively charged DNA moves toward the positive side. Larger fragments move slower and are located near the top whereas smaller fragments move faster and are near the bottom. Bands are stained but different shades indicate the amount of DNA each band contains. http://www.yourgenome.org/facts/what-is-gel-electrophoresis