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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 ...
During ATP production electrons can escape the mitochondrion and react with water, producing reactive oxygen species, ROS for short. ROS can damage macromolecules, including lipids, proteins and DNA, which is thought to facilitate the process of ageing. Electron transport chain in the inner mitochondrial membrane
Although oxidative phosphorylation is a vital part of metabolism, it produces reactive oxygen species such as superoxide and hydrogen peroxide, which lead to propagation of free radicals, damaging cells and contributing to disease and, possibly, aging and senescence.
In chemistry and biology, reactive oxygen species (ROS) are highly reactive chemicals formed from diatomic oxygen (O 2), water, and hydrogen peroxide. Some prominent ROS are hydroperoxide (O 2 H), superoxide (O 2-), [1] hydroxyl radical (OH.), and singlet oxygen. [2] ROS are pervasive because they are readily produced from O 2, which is ...
Mitochondrial ROS can promote cellular senescence and aging phenotypes in the skin of mice. [11] Ordinarily mitochondrial SOD2 protects against mitochondrial ROS. Epidermal cells in mutant mice with a genetic SOD2 deficiency undergo cellular senescence, nuclear DNA damage, and irreversible arrest of proliferation in a portion of their keratinocytes.
E. coli cells have revealed similarities to the aging process of higher organisms. The similarities include increased oxidation of cellular constituents and its target specificity, the role of antioxidants and oxygen tension in determining life span, and an apparent trade-off between activities related to reproduction and survival.
Reactive oxygen species levels increase with age in these mutant strains and show a similar pattern to the pattern of DNA damage increase with age. Thus it appears that superoxide dismutase plays a substantial role in preserving genome integrity during aging in S. cerevisiae. SOD2 knockout or null mutations cause growth inhibition on ...
Recent investigations suggest that complex I is a potent source of reactive oxygen species. [53] Complex I can produce superoxide (as well as hydrogen peroxide), through at least two different pathways. During forward electron transfer, only very small amounts of superoxide are produced (probably less than 0.1% of the overall electron flow).