用电场分离带电荷的生物分子如：DNA、RNA和蛋白质。由于结构内存在大量磷酸基团DNA和RNA带负电荷。蛋白质随着PH值不同携带不同电荷，但当某些化学试剂存在时会带负电荷。在凝胶电泳过程中，生物分子被注入由琼脂糖等惰性物质构成的固体胶块的孔里。当胶被放入溶液里并加上电场，生物分子根据大小相对于携带电量的比例移动和分离。生物分子可以被染色以便观察、分离和纯化，用于接下来的分析。电泳可用于从混合物中分离纯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).