用電場分離帶電荷的生物分子如：DNA、RNA和蛋白質。由于結構內存在大量磷酸基團DNA和RNA帶負電荷。蛋白質隨著PH值不同攜帶不同電荷，但當某些化學試劑存在時會帶負電荷。在凝膠電泳過程中，生物分子被注入由瓊脂糖等惰性物質構成的固體膠塊的孔里。當膠被放入溶液里并加上電場，生物分子根據大小相對于攜帶電量的比例移動和分離。生物分子可以被染色以便觀察、分離和純化，用于接下來的分析。電泳可用于從混合物中分離純化生物分子或分析生物分子。

 
The use of electrical fields to separate charged biomolecules such as DNA, RNA and proteins. DNA and RNA carry a net negative charge because of the numerous phosphate groups in their structure. Proteins carry a charge that changes with pH, but becomes negative in the presence of certain chemical detergents. In the process of “gel electrophoresis,” these biomolecules are put into wells of a solid matrix typically made of an inert substance such as agarose. When this gel is placed into a bath and an electrical charge applied across the gel, the biomolecules migrate and separate according to size in proportion to the amount of charge they carry. The biomolecules can be stained for viewing and isolated and purified from the gels for further analysis. Electrophoresis can be used to isolate pure biomolecules from a mixture or to analyze biomolecules (such as for DNA sequencing).