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Senescence (/ sɪˈnɛsəns /) 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. [ 1 ][ 2 ] However, the resulting effects of ...
Programmed cell death (PCD; sometimes referred to as cellular suicide[1]) is the death of a cell as a result of events inside of a cell, such as apoptosis or autophagy. [2][3] PCD is carried out in a biological process, which usually confers advantage during an organism's lifecycle. For example, the differentiation of fingers and toes in a ...
Cellular senescence is a phenomenon characterized by the cessation of cell division. [ 1 ][ 2 ][ 3 ] In their experiments during the early 1960s, Leonard Hayflick and Paul Moorhead found that normal human fetal fibroblasts in culture reach a maximum of approximately 50 cell population doublings before becoming senescent. [ 4 ][ 5 ][ 6 ] This ...
The mutation accumulation theory of aging was first proposed by Peter Medawar in 1952 as an evolutionary explanation for biological aging and the associated decline in fitness that accompanies it. [1] Medawar used the term ' senescence ' to refer to this process. The theory explains that, in the case where harmful mutations are only expressed ...
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. The Hayflick limit has been found to correlate with the length of the telomeric region at the end of chromosomes. During the process of DNA replication of a chromosome, small segments of ...
an irreversible state of dormancy, known as senescence; cell suicide, also known as apoptosis or programmed cell death; unregulated cell division, which can lead to the formation of a tumor that is cancerous; The DNA repair ability of a cell is vital to the integrity of its genome and thus to the normal functionality of that organism.
Genetic theories of aging propose that aging is programmed within each individual's genes. According to this theory, genes dictate cellular longevity. Programmed cell death, or apoptosis, is determined by a "biological clock" via genetic information in the nucleus of the cell. Genes responsible for apoptosis provide an explanation for cell ...
In biogerontology, the disposable soma theory of aging states that organisms age due to an evolutionary trade-off between growth, reproduction, and DNA repair maintenance. [1] Formulated by British biologist Thomas Kirkwood , the disposable soma theory explains that an organism only has a limited amount of resources that it can allocate to its ...