Separation of Large DNA Molecules -
The technique of gel electrophoresis is used for separation of DNA molecules of different sizes. However, DNA molecules of large size could not be handled in this technique. In recent years, a new technique called pulsed field gel electrophoresis (PFGE) has been used, for separation of large sized DNA molecules, sometimes representing whole chromosomes.

Using this technique, separation of DNA molecules belonging to each of the 16 individual chromosomes of yeast has become possible. In this technique, short pulses of electricity are used in two different directions and DNA is embedded and used in the form of agarose plugs to avoid fragmentation of large DNA molecules.

Using the technique of PFGE and a more refined technique CHEFE (countour clamped homogeneous electric field electrophoresis), genome of several fungi could be resolved into chromosomal bands and used for mapping of DNA sequences on specific chromosomes.