Apoptosis is the process of programmed cell death. It is a highly regulated and controlled process that occurs in multicellular organisms and some eukaryotic, single-celled microorganisms such as yeast. Apoptosis is used during early development to eliminate unwanted cells, such as those between the fingers of a developing hand, and in adults, it is used to rid the body of cells that have been damaged beyond repair. Apoptosis also plays a role in preventing cancer, as it eliminates cells that contain potentially dangerous mutations. If apoptosis is prevented, it can lead to uncontrolled cell division and the subsequent development of a tumor.

Some key features of apoptosis include:

• Morphological Characteristics: Apoptosis is characterized by distinct morphological changes, such as membrane blebbing, cell shrinkage, condensation of chromatin, and fragmentation of DNA.

• Energy-Dependent: Apoptosis is an energy-dependent process that requires ATP.

• DNA Degradation: One of the major characteristics of apoptosis is the degradation of DNA after the activation of Ca/Mg dependent endonucleases.

• Apoptotic Bodies: Apoptosis produces cell fragments called apoptotic bodies that phagocytes are able to engulf and remove before the contents of the cell can spill out onto surrounding cells and cause damage to them.

Apoptosis is critically important during various developmental processes, such as the nervous system and the immune system, which arise through overproduction of cells. This initial overproduction is then followed by the death of those cells that fail to establish functional synaptic connections or productive antigen specificities, respectively. Apoptosis also occurs as a defense mechanism, such as in immune reactions or when cells are damaged by disease or noxious agents.

Although many of the key apoptotic proteins have been identified, the molecular mechanisms of action or inaction of these proteins remain to be elucidated. There are currently strategies underway to develop drugs that would help reactivate the sensor and therefore activate apoptosis.