There are several methods for extracting genetic material from cells. Different methods use slightly different techniques or different combinations of reagents. However, the basic process is generally the same.
The desired cells are put into a tube and mixed with a special cocktail. The cocktail usually includes detergents, enzymes, and salts. Cell lysis, or the breaking open of the cells, occurs. The detergent breaks down the membrane lipids, enzymes remove the proteins, and the salt pulls out the DNA. DNA isolation occurs because salt neutralizes the charge of the DNA backbone and makes it less hydrophilic. Centrifuging the sample will cause the DNA to form a pellet at the bottom of the tube. The remaining cocktail can be poured off and the DNA pellet can be resuspended for further use.
Today, there are systems that will isolate and purify DNA automatically. Automated techniques can often work on more than one sample at a time, require little intervention, and produce more purified samples than manual techniques.