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Still life patterns are common in Life without Death: if there is no dead cell with three live neighbors, a pattern will remain unchanging for all future time steps. . However, because a cell, once alive, remains alive, the set of live cells grows monotonically throughout the evolution of a pattern, and there can be no oscillators (patterns that cycle through a repeating sequence of shapes ...
By preventing cells from reaching senescence one can achieve biological immortality; telomeres, a "cap" at the end of DNA, are thought to be the cause of cell aging. Every time a cell divides the telomere becomes a bit shorter; when it is finally worn down, the cell is unable to split and dies.
In biology, cell theory is a scientific theory first formulated in the mid-nineteenth century, that living organisms are made up of cells, that they are the basic structural/organizational unit of all organisms, and that all cells come from pre-existing cells.
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 ...
Whether or not viruses should be considered as alive is controversial. [ 33 ] [ 34 ] They are most often considered as just gene coding replicators rather than forms of life. [ 35 ] They have been described as "organisms at the edge of life" [ 36 ] because they possess genes , evolve by natural selection, [ 37 ] [ 38 ] and replicate by making ...
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.
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[L]ife, the form of the body, the properties and characters of its diverse parts, as resulting from the reciprocal play or struggle of all its elements, cells, fibres, tissues, organs, which act the one on the other, modify one the other, allot among them each its place and part, and lead all together to the final result, giving thus the ...