What is Apoptosis?
Apoptosis is the term used to describe the generally normal death of the cell in living organisms. Since new cells regenerate, cell death, or apoptosis is a normal and constant process in the body. Human embryos, for example, have far more cells than do adult humans. As the embryo develops, certain cells are selected for execution so that normal development takes place. When these cells do not go through apoptosis, they may cause deformity in the growing embryo. Apoptosis should not be confused with necrosis, cell death through disease or infection. Apoptosis is part of the cell’s function in the organism. When the processes of apoptosis are incomplete, this can lead to the development of both benign and malignant tumors, for instance. Apoptosis has several distinct stages. In the first stage the cell starts to become round as a result of the protein in the cell being eaten by enzymes that become active in the cell. Next, the DNA in the nucleus starts to come apart and shrink down. The
In normal tissue, cells that are no longer needed are rapidly eliminated without affecting the overall function of the tissue. In this process cells undergo an active and spontaneous suicide called programmed cell death. In fact, the majority of physiological cell deaths take the form of apoptosis. The word apoptosis is used, in contrast to necrosis, to describe the situation in which a cell actively pursues a course toward death upon receiving certain stimuli [1]. The morphological changes of apoptosis found in most cell types first involve contraction in cell volume and condensation of the nucleus. When this happens the intracellular organelles such as the mitochondria retain their normal morphology. As apoptosis proceeds, blebbing of the plasma membrane occurs, and the nucleus becomes fragmented. Finally, the cell itself fragments to form apoptotic bodies that are engulfed by nearby phagocytes. With respect to biochemical changes, it is known that the chromosomes become fragmented i
Programmed cell death is a series of events where a cell essentially shuts itself down and is eliminated. It is normal for many cells to die of apoptosis as the nervous system forms; it is part of constructing appropriate connections. Apoptosis is crucial for normal brain development and function, as researchers have discovered over the past decade or two. Just as a fruitful orchard results from judicious pruning, effective and efficient connections within the nervous system result from apoptosis.
Definition Apoptosis is a form of programmed cell death involving a biochemical cascade including such proteins as Bcl-2, Bax, Apaf-1 or apoptotic protease activating factor-1, caspases such as caspase-9, caspase-3, and caspase-7, as well as proteins involved in digestion of proteins, degradation of DNA, and phagocytosis. Apoptosis is a normal cellular process and is essential for the proper development and maintenance of the organism. Apoptosis is also necessary for the destruction of cells considered a threat such as cells infected with viruses, cells with DNA damage, cancerous cells, and cells of the immune system after they have fulfilled their function.
