Southern Blotting technique involves separation and identification of a specific DNA fragment. In Northern Blotting technique, the RNA is analysed rather than DNA. During southern blotting NaOH denatures DNA to form single stranded DNA which are transferred from gel to nitrocellulose membrane. In northern blotting, total RNA molecules are extracted and then mRNA molecules are isolated by using oligo (dT) cellulose Chromatography. RNA samples separated are transferred to a nylon membrane.