Agarose gel
electrophoresis is one of several physical methods for determining the
size of DNA. In this method, DNA is forced to migrate through a highly
cross-linked agarose matrix
in response to an electric current. In solution, the phosphates of the DNA are negatively
charged, and the molecule will therefore migrate to the positive (red) pole.
There are three factors that affect migration rate through a gel: size of the DNA, conformation of the DNA,
and ionic
strength of the running buffer.