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This article is about the biological definition of the word Lysis. For other uses, see Lysis (disambiguation).

Lysis (/ˈlsɪs/; Greek λύσις lýsis, "a loosing" from λύειν lýein, "to unbind") refers to the breaking down of a cell, often by viral, enzymic, or osmotic mechanisms that compromise its integrity. A fluid containing the contents of lysed cells is called a "lysate".

Many species of bacteria are subject to lysis by the enzyme lysozyme, found in animal saliva, egg white, and other secretions.[1] Phage lytic enzymes (lysins) produced during bacteriophage infection are responsible for the ability of these viruses to lyse bacterial cells.[2] Penicillin and related β-lactam antibiotics cause the death of bacteria through enzyme-mediated lysis that occurs after the drug causes the bacterium to form a defective cell wall.[3] If cell wall is completely lost, the bacterium is referred as a protoplast if penicillin was used on gram-positive bacteria, and spheroplast when used on gram-negative bacteria.


Main article: Cytolysis

Cytolysis occurs when a cell bursts due to an osmotic imbalance that has caused excess water to move into the cell.

Cytolysis can be prevented by several different mechanisms, including the contractile vacuole that exists in some paramecia, which rapidly pump water out of the cell. Cytolysis does not occur under normal conditions in plant cells because plant cells have a strong cell wall that contains the osmotic pressure, or turgor pressure, that would otherwise cause cytolysis to occur.


Oncolysis refers to the destruction of neoplastic cells or of a tumour.

It's also used to refer to the reduction of any swelling.[4]


Main article: Plasmolysis

Plasmolysis is the contraction of cells within plants due to the loss of water through osmosis. In a hypertonic environment, the cell membrane peels off of the cell wall and the vacuole collapses. These cells will eventually wilt and die unless the flow of water caused by osmosis can stop the contraction of the cell membrane.[5]

Immune response[edit]

Main article: Red Blood Cell

Erythrocytes' hemoglobin release free radicals in response to pathogens when lysed by them. This can damage the pathogens.[6][7]


Cell lysis is used to break open cells when it is desirable to avoid shear forces that would denature or degrade sensitive macromolecules, such as proteins and DNA. For example, lysis is used in western and Southern blotting to analyze the composition of specific proteins, lipids, and nucleic acids individually or as complexes. Depending upon the detergent used, either all or some membranes are lysed. For example, if only the cell membrane is lysed then gradient centrifugation can be used to collect certain organelles.

See also[edit]


  1. ^ P. Jollès, ed. (1996). Lysozymes--model enzymes in biochemistry and biology. Basel: Birkhäuser Verlag. pp. 35–64. ISBN 978-3-7643-5121-2. 
  2. ^ Nelson, D.; Loomis, L.; Fischetti, V. A. (20 March 2001). "Prevention and elimination of upper respiratory colonization of mice by group A streptococci by using a bacteriophage lytic enzyme". Proceedings of the National Academy of Sciences 98 (7): 4107–12. doi:10.1073/pnas.061038398. 
  3. ^ Scholar, E. M.; Pratt, W. B. (2000). The antimicrobial drugs (2nd ed.). Oxford University Press. pp. 61–64. 
  4. ^ "Oncolysis". Medical Dictionary. Farlex. Retrieved 27 March 2013. 
  5. ^ "Wiley InterScience : Journals : New Phytologist". Retrieved 2008-09-11. [dead link]
  6. ^ Red blood cells do more than just carry oxygen. New findings by NUS team show they aggressively attack bacteria too., The Straits Times, 1 September 2007
  7. ^ Jiang N, Tan NS, Ho B, Ding JL (October 2007). "Respiratory protein-generated reactive oxygen species as an antimicrobial strategy". Nature Immunology 8 (10): 1114–22. doi:10.1038/ni1501. PMID 17721536.