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This is called cellular senescence. Senescence can be induced by several factors, including telomere shortening, [37] DNA damage [38] and stress. Since the immune system is programmed to seek out and eliminate senescent cells, [39] it might be that senescence is one way for the body to rid itself of cells damaged beyond repair.
Depending on the severity of the DNA damage, the cells may no longer be able to undergo repair and either go through apoptosis or cell senescence. [8] Such senescent cells in mammalian culture and tissues retain DSBs and DDR markers. [14] It has been proposed that retained DSBs are major drivers of the aging process. Mutations in genes relating ...
Senescence (/ s ɪ ˈ n ɛ s ə n s /) or biological aging is the gradual deterioration of functional characteristics in living organisms. Whole organism senescence involves an increase in death rates or a decrease in fecundity with increasing age, at least in the later part of an organism's life cycle.
Overview of signal transduction pathways involved in apoptosis. Cell death is the event of a biological cell ceasing to carry out its functions. This may be the result of the natural process of old cells dying and being replaced by new ones, as in programmed cell death, or may result from factors such as diseases, localized injury, or the death of the organism of which the cells are part.
The typical normal human fetal cell will divide between 50 and 70 times before experiencing senescence. As the cell divides, the telomeres on the ends of chromosomes shorten. The Hayflick limit is the limit on cell replication imposed by the shortening of telomeres with each division. This end stage is known as cellular senescence.
Apoptosis is the programmed cell death of superfluous or potentially harmful cells in the body. It is an energy-dependent process mediated by proteolytic enzymes called caspases, which trigger cell death through the cleaving of specific proteins in the cytoplasm and nucleus. [13] The dying cells shrink and condense into apoptotic bodies.
Among the most commonly used cell lines are HeLa and Jurkat, both of which are immortalized cancer cell lines. [4] These cells have been and still are widely used in biological research such as creation of the polio vaccine, [5] sex hormone steroid research, [6] and cell metabolism. [7] Embryonic stem cells and germ cells have also been ...
With the selective shadow now shifted, humans must deal with these new selective pressures. [citation needed] Senescence is considered a by-product of physiology because our cell metabolism creates products that are toxic, we get mutations when we age, and we don't have enough stem cells that regenerate.