Science has demonstrated that certain deaths provide advantages to the harmonious development of an organism. "One of them is programmed cellular death, that consists in discarding trough life structures that the organism no longer needs," says Marcelino Cereijido, researcher at the Department of Physiology, Biophysics and Neurosciences at the Center of Research and Advanced Studies (Cinvestav).
These "suicides" take place when needed and each cellular structure is eliminated by accomplice substances (generated to accomplish their task without leaving a trail). "If this process were to be inhibit by genetic deficiencies or experimental manipulations, the consequence would not be eternal life but deformations or tumor appearances, since the cells would accumulate abnormally."
For example, the majority of cell death events take place towards the end of fetal life and the beginning of childhood, because its then when neural circuits and mechanisms that were used during gestation and are no longer needed get obliterated.
In this sense, during the formation of the nervous system, the brain contains many more neurons that it will need in the completion of its development; when the organ is fully formed the remaining cells perish.
"In specific, the cells that die are those that couldn't establish correct connections or the ones that did but were only useful during gestation. In fact, is estimated that the "building" of the brain implies, during the first year of life, the suicide of approximately half of the original neurons," said the researcher.
On the other hand, during its development, cells can receive signals that activate lethal genes, forcing them to obliterate themselves when the need arises. One way that this could occur is by increasing the production of proteins that facilitate the entry of calcium in the cell, mineral capable of activating molecules that destroy the intracellular architecture.
Another method is the fragmentation of DNA (where genes are located), RNA (which copies DNA to produce nutrients for the cell) and proteins, and provoking the macrophages to consume the rests of the cell in a process known as apoptosis.
Regarding cancerous cells that lead to the development of tumors, the researcher explains that this happens because they didn't "hear" the suicide order or generated their own commandment refusing to die, which allows them to survive and reproduce.
Creijido highlights that living depends in the capacity of self-repair, that implicates that skin cells be replaced by new ones, that the mucous membrane of the intestine be replaced every four days and blood cell be replaces every three months, processes where programmed cell death also intervenes.
However, this quality is lost with age, though the new knowledge takes over the repairt in the measure that scientific progress allows it. Towards the end of life in every organism, it cells, tissues and organs suffer several deficiencies that can't or are poorly fixed until the moment that one results fatal.
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