Lysis
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- This article deals with the biological definition of the word Lysis. For other meanings, see Lysis (disambiguation).
Lysis (Greek λύσις, lusis from luein = to separate) refers to the death of a cell by bursting, often by viral or osmotic mechanisms that compromise the integrity of the cellular membrane.
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[edit] Viral lysis
Viral lysis is the dissolution of cells by the action of a specific cytolysin, a substance that explicitly causes the death of the cell.
Viral lysis can be caused through the lytic cycle, where a phage infects a cell. The nucleic acid from the phage enters the cell, causing the assembly of more of the viruses. Eventually, the viruses break through the cell membrane of the cell, causing viral lysis.
[edit] Applications
Lysis is the first step after cell collection that is undergone in the process of DNA extraction. The cells to be analysed are made to burst with a specific chemical solution so that the components of the cell can be separated. This is the simplest method of cell disruption used to release the biological molecules in a cell and in a virus. It also helps the immune system and there are about 60 in each cell.
[edit] Cytolysis
Cytolysis is the lysis of cells in a hypotonic environment. Cytolysis is caused by excessive osmosis, or movement of water, towards the inside of a cell (hyperhydration). The cell membrane cannot withstand the osmotic pressure of the water inside, and so it explodes. Osmosis occurs from a region of high water potential to a region of low water potential passing through a semipermeable membrane, so these bursting cells are located in hypotonic environments.
Cytolysis can be prevented by several different mechanisms, including the contractile vacuole that exists in some paramecium which rapidly pump water out of the system 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.
[edit] 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.
