The exact causes of chronic kidney failure are unknown, although the debilitating loss of healthy kidney tissue may be a natural endpoint for several readily recognizable conditions, including advanced dental disease and a variety of kidney infections, inflammations and obstructions.
Sodium chloride was needed to ensure the proteins in the cell aren't separated from the rest of the solution with the DNA. Okay, the person above does not understand Chemistry nor the English language. The sodium chloride, NaCl, is a polar molecule, which would help separate an emulsion of two layers in an acid-base extraction. Since NaCl is polar, it would be easily dissolved into the solution and tie up the different layer molecules.
DNA extraction is the process by which a cell is broken open to expose and extract its DNA. This is done by breaking down and emulsifying the fat and proteins that make up the cell's membrane through the addition of both salt and detergent solutions. Then the DNA is separated by by adding alcohol and centrifuging the resulting solution.