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  2. Reactive oxygen species - Wikipedia

    en.wikipedia.org/wiki/Reactive_oxygen_species

    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 ...

  3. Respiratory burst - Wikipedia

    en.wikipedia.org/wiki/Respiratory_burst

    Respiratory burst (or oxidative burst) is the rapid release of the reactive oxygen species (ROS), superoxide anion (O − 2) and hydrogen peroxide (H 2 O 2), from different cell types. This is usually utilised for mammalian immunological defence, but also plays a role in cell signalling.

  4. Reactive nitrogen species - Wikipedia

    en.wikipedia.org/wiki/Reactive_Nitrogen_Species

    Reactive nitrogen species act together with reactive oxygen species (ROS) to damage cells, causing nitrosative stress. Therefore, these two species are often collectively referred to as ROS/RNS. Reactive nitrogen species are also continuously produced in plants as by-products of aerobic metabolism or in response to stress. [3]

  5. Reactive nitrogen - Wikipedia

    en.wikipedia.org/wiki/Reactive_nitrogen

    Reactive nitrogen ("Nr"), also known as fixed nitrogen [1], refers to all forms of nitrogen present in the environment except for molecular nitrogen (N 2 ). [ 2 ] While nitrogen is an essential element for life on Earth, molecular nitrogen is comparatively unreactive, and must be converted to other chemical forms via nitrogen fixation before it ...

  6. Marine biogeochemical cycles - Wikipedia

    en.wikipedia.org/wiki/Marine_biogeochemical_cycles

    The six aforementioned elements are used by organisms in a variety of ways. Hydrogen and oxygen are found in water and organic molecules, both of which are essential to life. Carbon is found in all organic molecules, whereas nitrogen is an important component of nucleic acids and proteins.

  7. Respiratory complex I - Wikipedia

    en.wikipedia.org/wiki/Respiratory_complex_I

    This can take place during tissue ischaemia, when oxygen delivery is blocked. [58] Superoxide is a reactive oxygen species that contributes to cellular oxidative stress and is linked to neuromuscular diseases and aging. [59] NADH dehydrogenase produces superoxide by transferring one electron from FMNH 2 (or semireduced flavin) to oxygen (O 2 ...

  8. Aquatic respiration - Wikipedia

    en.wikipedia.org/wiki/Aquatic_respiration

    In species like the spiny dogfish and other sharks and rays, a spiracle exists near the top of the head that pumps water into the gills when the animal is not in motion. [5] In some fish, capillary blood flows in the opposite direction to the water, causing countercurrent exchange. The muscles on the sides of the pharynx push the oxygen ...

  9. Biological roles of the elements - Wikipedia

    en.wikipedia.org/wiki/Biological_roles_of_the...

    A large fraction of the chemical elements that occur naturally on the Earth's surface are essential to the structure and metabolism of living things. Four of these elements (hydrogen, carbon, nitrogen, and oxygen) are essential to every living thing and collectively make up 99% of the mass of protoplasm. [1]