A3243G
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Apoptosis
Apoptosis describes programmed Death or Suicide of Cells.
Apoptosis is a natural and ongoing method of maintaining a healthy body.
The human body
replaces perhaps a million cells a second. Over the course of a year, that is
roughly equal to the number of cells in the human body. Without an orderly
process for getting rid of cells, we would double in size within a year.
Too little or too
much apoptosis plays a role in a great many diseases. When programmed cell death
does not work right, cells that should be eliminated may hang around and become
immortal. For example, in cancer and leukaemia.
When apoptosis works
overly well, it kills too many cells and inflicts grave tissue damage. This is
the case in strokes and neurodegenerative disorders such as
Alzheimer, Huntington and Parkinson diseases.
A cell may trigger it's own suicide in response to a
diverse set of signals that include physical and genetic damage, oxygen or
nutrient deprivation, loss of contact with neighbouring cells, and infection by
viruses.
Apoptotic cell
death is very rapid, typically taking less than one hour. During apoptosis, the
cell shrinks and its surface membrane takes on a characteristic "boiling"
appearance with the formation of blebs and pinched off vesicles. The cell's DNA is
cut up by
enzymes called nucleases. Finally, the whole cell collapses into membrane-bound
apoptotic cell fragments that are rapidly "eaten" by neighbouring cells via the
process of phagocytosis.
Apoptosis is therefore both an efficient way of killing
unwanted or damaged cells and of packaging the remnants for rapid removal.
See Also
Mitosis
Author: Andy Collinson.
Although I don't have any medical qualifications,
as a sufferer of Diabetes, Deafness and Tinnitus caused by the A3243G mtDNA defect,
I do have a very keen interest in the subject.
Date Page Updated:
25 April 2005
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