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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
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 ...
Reactive oxygen species are implicated in cellular activity to a variety of inflammatory responses including cardiovascular disease. They may also be involved in hearing impairment via cochlear damage induced by elevated sound levels , in ototoxicity of drugs such as cisplatin , and in congenital deafness in both animals and humans.
8-Oxoguanine (8-hydroxyguanine, 8-oxo-Gua, or OH 8 Gua) is one of the most common DNA lesions resulting from reactive oxygen species [2] modifying guanine, and can result in a mismatched pairing with adenine resulting in G to T and C to A substitutions in the genome. [3] In humans, it is primarily repaired by DNA glycosylase OGG1.
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.
Cells can also be induced to senesce by DNA damage in response to elevated reactive oxygen species (ROS), activation of oncogenes, and cell-cell fusion. Normally, cell senescence is reached through a combination of a variety of factors (i.e., both telomere shortening and oxidative stress). [13]
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.
Supplementary oxygen administration is widely used in emergency and intensive care medicine and can be life-saving in critical conditions, but too much can be harmful and affects a variety of pathophysiological processes. Reactive oxygen species are known problematic by-products of hyperoxia which have an important role in cell signaling pathways.