Electrophoresis is a technique commonly used in the lab to separate charged molecules, like DNA, according to size.
Gel electrophoresis is a technique commonly used in laboratories to separate charged molecules like DNA?, RNA? and proteins? according to their size.
Charged molecules move through a gel when an electric current is passed across it.
An electric current is applied across the gel so that one end of the gel has a positive charge and the other end has a negative charge.
The movement of charged molecules is called migration. Molecules migrate towards the opposite charge. A molecule with a negative charge will therefore be pulled towards the positive end (opposites attract!).
The gel consists of a permeable matrix, a bit like a sieve, through which molecules can travel when an electric current is passed across it.
Smaller molecules migrate through the gel more quickly and therefore travel further than larger fragments that migrate more slowly and therefore will travel a shorter distance. As a result the molecules are separated by size.