Apoptosis It is a Greek word which means

Apoptosis

• It is a Greek word which means “falling off” or “dropping off”. • It is the process of programmed cell death in which body cells die and get phagocytosed under genetic control. • Genes of the own cells plays important role on its death. • Hence it is also called as Cell suicide

Physiological Significance Apoptosis play an important role during embryonal development and also in adulthhooh For eample… 1. It is responsible for regression of duct system during sex differentiation in the foetus. 2. Death of neurons in CNS during brain development and formation of synapse.

3. Degeneration of many tissues like web in the finger during fetal development. 4. It is responsible for cyclical shedding of endometrium at the time menstrual cycle.

Mechanism of Apoptosis • Activation of Cystein proteases in the cell called Caspases triggers apoptosis by activates apoptotic gene. • Normally Caspases inactive form in the cell and activated by stimuli called external and internal stimuli • Internal stimuli: Mitochondria release cytochrome and protein called smac that causes activation of the caspase 9, which induces apoptosis by destroy the DNA in nucleus

External stimuli: These are the various ligands like tumar necrosis factor that bind with cell surface to induce apoptosis by activates the enzyme caspase 8, which promtes DNA fragmentation and chromatin condensation.

Application Identification of components of the cell death control, mechanism and linkage of abnormalities in cell death to human disease like cancer and degenerative diseases. Understanding the concept of apoptosis has promoting role in future regenerative medicine