Disadvantages Of Apoptosis

4. Apoptosis

Multicellular organisms require tight control of its cell populations, since overall number and cell types as well as cell locations need to be correct to produce a healthy and functional organism. Cell numbers are controlled by their rate of proliferation, but also by cell death. This ratio must be balanced to keep an organism in correct size. Cells can undergo apoptosis or necrosis. Cells that die as a result of acute injury typically swell and burst and undergo necrosis. Unnecessary or suitably damaged cells are removed by programmed cell death, of which most common is apoptosis. Apoptosis is apparent during development, for example to form separate and correctly shaped digits numerous cells between the digits must be removed. During neuronal development many neurons die to match the number of targets cells that require innervation. Also in adult human billions of cells in the bone marrow and intestine die each day. Apoptosis also occurs during DNA damage and different stresses, if the damage is high enough. This allows organism to get rid of nonfunctioning cells and it prevents the development of cancer by removing cell with potentially cancer-promoting mutations.

In apoptosis cells die without bursting or causing inflammation reaction. Cell undergoing apoptosis shrinks and condenses, cytoskeleton collapses, the nuclear envelope

During apoptosis inactive procaspases are activated to caspases often initially in a distinct activation complexes DISC or apoptosome. Cells have at least two distinct pathways for apoptosis. Extrinsic pathway is activated by extracellular ligands binding to death receptors. Intrinsic pathway is activated by intracellular signals in response to stresses. Extracellular signal proteins and Bcl2 and IAP proteins are major regulators of apoptosis only allowing apoptosis when it is beneficial for the organism (Alberts et al.,