DNA Purification and Extraction

Swiss Biologist Friedrich Miescher was the first person to isolate a DNA. The process refers to both extraction and purification of DNA from the given sample such as blood, swab, plant tissue, animal tissue, bacterial cells, etc. A general protocol involves homogenization of cells using a physical method like the use of mortar and pestle or automated homogenizer. This may be followed by a series of chemical treatment with detergents to remove fats, rupture cellular membranes and then by using Chloroform & further centrifugation, DNA can be separated from the cellular debris. A high temperature may be maintained to promote cell lysis. A buffer like Tris to maintain pH is used throughout. Ethanol or isopropanol is then used to precipitate out DNA. Purification may involve many steps like the use of proteinase or phenol-chloroform extraction to eliminate protein impurities or RNAse to remove RNA.

Kits for extraction and purification of DNA specific to the source of DNA are available for ready-to-use, or separate components can be used to develop a standardized protocol.