Question

Apoptosis – know what this is and when it would occur

Answer 1

Apoptosis ,also referred to as programmed cell death play role in eliminating highly proliferating and mutated cells from organism and thus a major target for treatment of cancer.In general, Apoptosis can be inititiated by two pathways: intrinsic pathway and extrinsic pathway. Extrinsic pathway involves binding of Fas receptor to FasL , that leads to (Death Inducing Signalling Complex)DISC complex formation. This complex contains Fas Associated Death Domain(FADD), caspase 8 and caspase 10 which signals for the cell death. Studies suggested that there was an upregulation in fas and cleavage of Bid to tBid which then transferred to mitochondria to induce apoptosis.While the intrinsic or mitochondrial pathway can be initiated by showing apoptotic DNA fragmentation, breakdown of caspase 3, depolarisation of mitochondrial membrane that leads to increase in cytochrome c levels and inhibition of Ca2+ ATPase occurs. Release of cyt c results in activation of caspase 9 from procaspase 9 which further activates the apoptotic pathway. caspases have the proteolytic activity.

apoptosis is an energy dependent biochemical mechanism of programmed cell death. it is the genetically programmed process of deliberate suicide by an unwanted cell in a multicellular organism during embryogenesis, metamorphosis, and tisuue turnover. it is the capacity of a cell to respond to a stimulus by initiating a pathway that leads to its cell death. apoptotic cells become more compact, blebbing occur at membranes, chromatin becomes condensed and DNA is fragmented. dying cells shrink and condense and fragment releasing small membrane bound apoptotic bodies that are phagocytosed by the surroundimg cells.