Power, Sex, Suicide by Nick Lane (2006) part 5 "Murder or suicide" mentions that apoptosis has two main functions:
- prevent cancer
- but it is also an important part of body development, e.g. fingers are separated because cells between them kill themselves. Otherwise we would have webbed feet like ducks. There is also a lot of apoptosis during the development of the brain. This has been observed notably in C. elegans see also: Section "C. elegans cell lineage".
Power, Sex, Suicide by Nick Lane (2006) part 5 "Murder or suicide" mentions that the key events that leads to apoptosis is when certain proteins normally present in the inner mitochondrial membrane spill out, and that this often happens when free radicals are produced in excess: the cell is really not doing well in those cases. This point suggests that the initial mitochondrial endosymbiosis happened due to a parasite that lived inside another cell. It mentions that even today we see parasites kill the host cell when they feel that the cell does not have many nutrients. This frees the parasites to then infect other cells.
Articles by others on the same topic
A regulated form of cell death. Measuring it helps distinguish failed cell specification from selective loss of an already specified biological population.
Typical execution includes protease activation, chromatin changes and packaging of cellular material for removal. Clearance by other cells can limit leakage of intracellular contents. The process is therefore more specific than any observation of reduced cell number or a cell failing to divide. [ref]
Molecular Biology of the Cell, 4th edition by Bruce Alberts and others. Chapter 17, Programmed Cell Death