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Cellular senescence is a phenomenon characterized by the cessation of cell division. [1] [2] [3] ... [15] (see DNA damage theory of aging). ...
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.
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.
It is in line with the 12 hallmarks of aging, such as chronic inflammation and cellular senescence, that happen on a molecular level as people grow older. It also explains how older adults ...
The DNA damage theory of aging proposes that aging is a consequence of unrepaired ... (by increasing apoptosis or cellular senescence) ... If a cell retains DNA ...
One of the main criticisms of the free radical theory of aging is directed at the suggestion that free radicals are responsible for the damage of biomolecules, thus being a major reason for cellular senescence and organismal aging. [26]: 81 Several modifications have been proposed to integrate current research into the overall theory.
Therefore, a greater investment in growth and reproduction would result in reduced investment in DNA repair maintenance, leading to increased cellular damage, shortened telomeres, accumulation of mutations, compromised stem cells, and ultimately, senescence. Although many models, both animal and human, have appeared to support this theory ...
The two theories; non-adaptive, and adaptive, are used to explain the evolution of senescence, which is the decline in reproduction with age. [8] The non-adaptive theory assumes that the evolutionary deterioration of human age occurs as a result of accumulation of deleterious mutations in the germline. [8]