Cell lysis is used in laboratories to break open cells and purify or further study their contents. Lysis in the laboratory may be affected by enzymes or detergents or other chaotropic agents . Mechanical disruption of cell membranes, as by repeated freezing and thawing, sonication , pressure, or filtration may also be referred to as lysis. Many laboratory experiments are sensitive to the choice of lysis mechanism; often it is desirable to avoid mechanical shear forces that would denature or degrade sensitive macromolecules, such as proteins and DNA , and different types of detergents can yield different results. The unprocessed solution immediately after lysis but before any further extraction steps is often referred to as a crude lysate .