text: * Cells that are to be studied need to be collected.
  * Breaking the cell membranes open exposes the DNA along with the cytoplasm within (cell lysis).
  ** Lipids from the cell membrane and the nucleus are broken down with  detergents and surfactants.
  ** Breaking down proteins by adding a protease (optional).
  ** Breaking down RNA by adding an RNase (optional).
  * The solution is treated with a concentrated salt solution (saline) to make debris such as broken proteins, lipids, and RNA clump together.
  * Centrifugation of the solution, which separates the clumped cellular debris from the DNA.
  * DNA purification from detergents, proteins, salts, and reagents is used during the cell lysis step. The most commonly used procedures are:
  **Ethanol precipitation usually by ice-cold ethanol or isopropanol. Since DNA is insoluble in these alcohols, it will aggregate together, giving a pellet upon centrifugation. Precipitation of DNA is improved by increasing ionic strength, usually by adding sodium acetate.
  ** Phenol–chloroform extraction in which phenol denatures proteins in the sample. After centrifugation of the sample, denatured proteins stay in the organic phase while the aqueous phase containing nucleic acid is mixed with chloroform to remove phenol residues from the solution.
  ** Minicolumn purification relies on the fact that the nucleic acids may bind (adsorption) to the solid phase (silica or other) depending on the pH and the salt concentration of the buffer.
  Cellular and histone proteins bound to the DNA can be removed either by adding a protease or having precipitated the proteins with sodium or ammonium acetate or extracted them with a phenol-chloroform mixture before the DNA precipitation.
  After isolation, the DNA is dissolved in a slightly alkaline buffer, usually in a TE buffer, or in ultra-pure water.