Purpose: DNA gel electrophoresis attempts to separate DNA fragments according to the size of the fragments.
Function: The DNA sample is loaded into the wells of the gel and a current is applied to the electrophoresis chamber which also contains a salt water buffer. The DNA is moves towards the positive electrode in response to an applied current. Larger DNA fragments move slower through the agarose molecules in the gel.
Application: Gel electrophoresis can be used to analyze and compare the RFLPs of an unknown genetic sample to known genetic samples. For example, DNA evidence at a crime scene can be compared to a series of potential suspects.