In multicellular organism, cells that are no longer needed or are a threat to the organism are destroyed by a tightly regulated cells suicide process known as programmed cell death or apoptosis. It is a natural way of destroying its own cell which means , the destruction of cells through chemical agents or radiation cannot be called as apoptosis .Neither Necrosis is related by any way to apoptosis cause in case of Necrosis cell dies due to either lack of blood supply or introduction of toxin.
This is some how strange to know that why a cell intentionally kills itself?
But, this process confers a large number of advantages to human life in many ways.It is necessary in the development,maintenance and regulation of cells during physiological as well as pathological conditions
As we know that our body contains millions of cells in every network and each cell present in our body has a certain life span(the time when the cell stops functioning) and are no longer useful. Also ,the process towards the formation of new cells in the body goes on side by side. If the old cells are not destroyed, this results in accumulation of old and new developing cells which results in the formation of tumor in certain parts of the body. Also these tumors formed can result to chronic diseases like cancer. This portrays the importance of lack of apoptosis in our body.
If Cancer is caused by too less apoptosis unwanted increment of cell suicide process can also arise many neuro-degenerative diseases like Parkinson’s and Alzheimer’s Diseases where too much death of cell is taken to account for the loss of neurons .
To understand apoptosis in a better way, we have numerous other examples .
Somehow due to mutations or various other reasons, if the base pair of DNA gets altered ,the severe effects can occur in the functioning of cell. The cell at first,tries to cure it but in case no alternatives are left ,apoptosis can help in the destruction of that particular cell which posses the potentiality to interrupt the whole system and functioning of the body.
Likewise,in the world of pathogens its not surprising to get infected and that particular infected cell can soon infect the nearby cells if not destroyed on time .So again what comes is Apoptosis- which is the only means to stop the growth of pathogens.
Apoptosis also plays an important part in immune system.Any infective or self reactive matured T-lymphocytes can be removed through induction of apoptosis if the cells are not ensuring their efficacy against foreign antigens on being tested or if found exerting influence over the normal healthy cells of the body.
But in all these cases ,apoptosis does not happen immediately .The decision to undergo apoptosis is made only in the situations where no alternatives are left to cure the cell .After the decision is made, the cell undergoes some series of biological transformations. At first , shrinking of cytoplasm occurs leading to contraction of protoplasm and nucleus inside thereby the blebs are formed, known to be the apoptotic bodies, those which can be easily engulfed by the phagocytic cells leaving no waste residues to the environment which signifies its positive attitude towards environment too.
In an organism apoptosis takes place by two Pathways.
When apoptotic signals are received from outside the body ,it is termed as extrinsic pathway where as internal signals give rise to intrinsic pathway.In either of the cases, Apoptosis is executed by the proteolytic enzymes called caspases which trigger the cell death by cleaving the specific proteins in the cytoplasm and nucleus. Caspases exist in all cells as inactive precursors or procaspases which get activated by cleavage and activates other caspases and form a caspase cascade .The activation process is initiated by either extracellular or intracellular death signals causing intracellular adaptor molecules to aggregate and activate procaspases. Its activation is also regulated by members of Bcl-2 and IAP protein families .
The importance of understanding the concept apoptosis is vital because programmed cell death is a component of both health and disease, being initiated by various physiologic and pathologic stimuli. Moreover, the widespread involvement of apoptosis in the pathophysiology of disease lends itself to therapeutic intervention at many different checkpoints. In addition, a better knowledge of apoptosis, and other variants of programmed cell death, at the molecular level can deeper insight into various disease processes and may thus influence therapeutic strategy.
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