Search results
Results from the WOW.Com Content Network
The DNA damage theory of aging proposes that aging is a consequence of unrepaired accumulation of naturally occurring DNA damage. Damage in this context is a DNA alteration that has an abnormal structure. Although both mitochondrial and nuclear DNA damage can contribute to aging, nuclear DNA is the main subject of this analysis.
The free radical theory of aging states that organisms age because cells accumulate free radical damage over time. [ 1 ] A free radical is any atom or molecule that has a single unpaired electron in an outer shell. [ 2 ] While a few free radicals such as melanin are not chemically reactive, most biologically relevant free radicals are highly ...
The antagonistic pleiotropy hypothesis (APT) is a theory in evolutionary biology that suggests certain genes may confer beneficial effects early in an organism's life, enhancing reproductive success, while also causing detrimental effects later in life, contributing to the aging process. APT was first proposed in a 1952 paper on the ...
Organismal senescence is the aging of whole organisms. Actuarial senescence can be defined as an increase in mortality or a decrease in fecundity with age. The Gompertz–Makeham law of mortality says that the age-dependent component of the mortality rate increases exponentially with age. Aging is characterized by the declining ability to ...
Society portal. v. t. e. Gerontology (/ ˌdʒɛrənˈtɒlədʒi / JERR-ən-TOL-ə-jee) is the study of the social, cultural, psychological, cognitive, and biological aspects of aging. The word was coined by Ilya Ilyich Mechnikov in 1903, from the Greek γέρων (gérōn), meaning "old man", and -λογία (-logía), meaning "study of". [ 1 ...
The hallmarks of aging are the types of biochemical changes that occur in all organisms that experience biological aging and lead to a progressive loss of physiological integrity, impaired function and, eventually, death. They were first listed in a landmark paper in 2013 [1] to conceptualize the essence of biological aging and its underlying ...
A telomere is a region of repetitive sequencesat each end of the chromosomesof most eukaryotes. Telomeres protect the end of the chromosome from DNA damageor from fusion with neighbouring chromosomes. The fruit fly Drosophila melanogasterlacks telomerase, but instead uses retrotransposonsto maintain telomeres.
These non-replicating cells do not commonly give rise to cancer, but they do accumulate DNA damages with time that likely contribute to aging (see DNA damage theory of aging). In a non-replicating cell, a single-strand break or other type of damage in the transcribed strand of DNA can block RNA polymerase II-catalysed transcription. [97]