What is a apoptosis? What causes it? Is it helpful or harmful?

Question

Does it stop happening at a certain age to gametes?

Answer 1

Apoptosis is incredibly important. It is a completely designed, intended form of cells to die (compared to necrosis, which is accidental death of cells). On a very superficial level, cancer is a result of LOSING control of apoptosis.

There are 2 apoptotic mechanisms, the intrinsic and extrinsic pathways. The extrinsic mechanism is stimulated from outside the cell (hence the nomenclature). It involved a ligand (something called Fas-Ligand) binding to a receptor (Fas), and stimulating cell destruction by destroying DNA. The other mechanism is the intrinsic mechanism, which is controlled from inside the cell after it has been damaged. This involved cytochrome C release from mitochondria.

Both pathways involve the use of CASPASE proteins that are involved in degrading DNA.

Answer 2

Pre-programmed cell death. It's pre-determined by your genes. Some cells must die (like skin to form epidermis), others will "suicide" to form edges (eyelids, fingers) in embryo, others will die of... old age: after many divisions.

In the end it's both helpful (because it's the natural event within your body) and harmful because in the end it will kill you (but if not OF something then everyone will die of old age and apoptosis)