Editing Reactive oxygen species (section)

===Oxidative damage===
In [[aerobic organism]]s the energy needed to fuel biological functions is produced in the [[mitochondria]] via the [[electron transport chain]]. Reactive oxygen species (ROS) with the potential to cause [[cell (biology)|cellular]] damage are produced along with the release of energy. ROS can damage lipids, [[DNA]], [[RNA]], and proteins, which, in theory, contributes to the [[physiology]] of [[aging]].

ROS are produced as a normal product of [[cellular metabolism]]. In particular, one major contributor to oxidative damage is [[hydrogen peroxide]] (H<sub>2</sub>O<sub>2</sub>), which is converted from [[superoxide]] that leaks from the mitochondria. [[Catalase]] and [[superoxide dismutase]] ameliorate the damaging effects of hydrogen peroxide and superoxide, respectively, by converting these compounds into [[oxygen]] and [[hydrogen peroxide]] (which is later converted to water), resulting in the production of [[benign]] [[molecule]]s. However, this conversion is not 100% efficient, and residual peroxides persist in the cell. While ROS are produced as a product of normal cellular functioning, excessive amounts can cause deleterious effects.<ref name="isbn0-8247-1723-6">{{Cite book |title=Understanding the process of aging: the roles of mitochondria, free radicals, and antioxidants |vauthors=Patel RP, T Cornwell T, Darley-Usmar VM |publisher=Marcel Dekker |year=1999 |isbn=0-8247-1723-6 |veditors=Packer L, Cadenas E |location=New York, NY |pages=39–56 |chapter=The biochemistry of nitric oxide and peroxynitrite: implications for mitochondrial function}}</ref>