| In apoptosis (programmed cell death), cell volume shrinks dramatically and the cytoskeleton is modified. The membrane shrivels, and little apoptotic bodies (sometimes containing intact organelles) splinter off. As the DNA disintegrates into fragments, macrophages phagocytose the apoptotic bodies and the cell itself. This phagocytosis ensures that intracellular contents are not released into the surrounding tissue, thus preventing an inflammatory response. Apoptosis is not only essential for avoiding overpopulation, but can be induced by cytotoxic T cells or natural killer cells to obliterate infected cells. To the right are several genes involved in apoptosis; disruption of inhibitors can be cancerous. |
|
| Gene |
Function |
Apoptosis |
| bcl-2 |
Prevents apoptosis. |
Inhibits |
| bax |
Opposes bcl-2. |
Promotes |
| bcl-XL |
Bbcl-Long prevents apoptosis. |
Inhibits |
| bcl-XS |
Bcl-Short opposes bcl-XL. |
Promotes |
| caspase |
The caspases are proteases. |
Promotes |
| Fas |
Induces apoptosis. |
Initiates |
|
