The agarose gel consists of microscopic pores that act as a molecular sieve which separates molecules based upon the charge, size and shape.Agarose gel electrophoresis can also be used to separate other charged biomolecules such as RNA and proteins.Agarose is isolated from the seaweed genera Gelidium and Gracilaria and consists of repeated agarobiose (L- and D-galactose) subunits.The concentration of agarose in a gel depends on the sizes of the DNA fragments to be separated, with most gels ranging between 0.5%-2%.