What are the different methods of DNA and RNA extraction?

Answer 1

DNA extraction is done by three methods: * Organic extraction * inorganic extraction * solid state method In organic extraction, phenol and chloroform are used to create on organic phase in which cells are lysed and DNA is freed. The DNA remains in the aqueous phase. Ethyl alcohol is used to precipitate the DNA. In the inroganic methos, NaCl and EDTA are used for cell lysis. Following this, an approach similar to the organic method is followed. In solid state extraction, DNA is first precipitated in the presence of high slat and low pH conditions. The precipitated DNA is then adsorbed on to a filter membrane surface.

Answer 2

This procedure is complicated by the ubiquitous presence of ribonuclease enzymes in cells and tissues, which can rapidly degrade RNA. Several methods are used in molecular Biology to isolate RNA from samples, the most common of these is Guanidinium thiocyanate-phenol-chloroform extraction This method often uses a proprietary formulation of this reagent called Trizol.

Answer 3

The three basic steps of DNA extraction are:

1. Cell lysis - bursting opening the cell OR bacterium to liberate cell contents into the bulk of the medium
2. Precipitating proteins - this process separates nucleic acids from proteins, which is one of the two major contaminants in DNA extraction (the other major contaminant being RNA)
3. DNA purification - Typically, high salt buffers and organic chemicals are used during step 2 and therefore, they must be removed and the DNA must be placed in a suitable buffer that will maintain its integrity. This is the function of step 3.