Definition of Electrophoresis

Electrophoresis: A process by which molecules (such as proteins, DNA, or RNA fragments) can be separated according to size and electrical charge by applying an electric current to them. Each kind of molecule travels through the medium at a different rate, depending on its electrical charge and molecular size.

Historically, many substances including starch gels and paper have served as media for electrophoresis. However, agarose and acrylamide gels are the media currently in common use for the electrophoresis of proteins and nucleic acids. The current forces the molecules through pores in a thin layer of gel, a firm jelly-like substance. The gel can be made so that its pores are just the right dimensions for separating molecules within a specific range of sizes and shapes. Smaller fragments usually travel further than large ones. The process is sometimes called gel electrophoresis.