Electrophoresis

Electrophoresis is used as a method of separating DNA according to size, using a porous gel as a filter (usually polyacylamide gels are used). By applying an electric current, the molecules of DNA are made to move through the gel towards the positive electrode (anode), with the smaller or more compact strands travelling the fastest. This produces distinct bands of DNA, which can be identified by comparing with a known DNA sample 'ladder' run simultaeously. Any molecule with a net charge, such as proteins, can also be seperated using this technique.

The mobility of charges molecules are influenced by:

• Net Charge of molecule. Negitive charged molecules move towards the positive end of the electrode (anode) while positive charged molecule move towards the negitive end of electrode (cathode). 
• Size of molecule
• Shape
• Electrical field strength applied