Question

In agarose gel electrophoresis, why do DNA fragments move toward the positive electrode?

Options

• DNA molecules carry an overall negative charge

• Ultraviolet light induces a temporary positive dipole in DNA

• DNA molecules carry an overall positive charge

• Agarose gel repels neutral molecules toward the cathode

Answer 1

DNA molecules are negatively charged and therefore migrate toward the positive electrode (anode) in an electric field. Smaller fragments navigate the agarose gel matrix faster than larger ones.