A crude lysate is the solution produced when cells are destroyed by disrupting their cell membranes, often with detergent or other chaotropic agent (sometimes by freeze-thawing (liquid nitrogen, 37°C, 1 min vortex), in a process known as cytolysis. This releases the contents within the cell. Crude cell lysates are routinely produced in biochemistry and cell biology laboratories during the process of protein purification, although purified cellular organelles can also be retrieved from the solution. After a crude lysate has been generated, the first step in processing a crude lysate is often ultracentrifugation, which separates the solution into distinct bands containing organelles, membrane lipids, proteins, and nucleic acids. The crude lysate can also be analyzed directly without further processing or purification by such methods as Coomassie blue staining of polyacrylamide gels or Western blotting.