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  2. Oxygen - Wikipedia

    en.wikipedia.org/wiki/Oxygen

    Free oxygen began to outgas from the oceans 3–2.7 billion years ago, reaching 10% of its present level around 1.7 billion years ago. [ 89 ] [ 91 ] The presence of large amounts of dissolved and free oxygen in the oceans and atmosphere may have driven most of the extant anaerobic organisms to extinction during the Great Oxygenation Event ...

  3. Chemical bond - Wikipedia

    en.wikipedia.org/wiki/Chemical_bond

    In this type of bonding, each atom in a metal donates one or more electrons to a "sea" of electrons that reside between many metal atoms. In this sea, each electron is free (by virtue of its wave nature) to be associated with a great many atoms at once. The bond results because the metal atoms become somewhat positively charged due to loss of ...

  4. Phosphodiester bond - Wikipedia

    en.wikipedia.org/wiki/Phosphodiester_bond

    The 5' end has a 5' carbon attached to a phosphate, and the other end, the 3' end, has a 3' carbon attached to a hydroxyl group. In chemistry, a phosphodiester bond occurs when exactly two of the hydroxyl groups (−OH) in phosphoric acid react with hydroxyl groups on other molecules to form two ester bonds.

  5. Quizlet - Wikipedia

    en.wikipedia.org/wiki/Quizlet

    Quizlet is a multi-national American company that provides tools for studying and learning. [1] Quizlet was founded in October 2005 by Andrew Sutherland, who at the time was a 15-year old student, [ 2 ] and released to the public in January 2007. [ 3 ]

  6. Haldane effect - Wikipedia

    en.wikipedia.org/wiki/Haldane_effect

    In the oxygen-rich capillaries of the lung, this property causes the displacement of carbon dioxide to plasma as low-oxygen blood enters the alveolus and is vital for alveolar gas exchange. The general equation for the Haldane Effect is: H + + HbO 2 ⇌ H + Hb + O 2; However, this equation is confusing as it reflects primarily the Bohr effect.

  7. Oxidative phosphorylation - Wikipedia

    en.wikipedia.org/wiki/Oxidative_phosphorylation

    The naked mole rat has the unique ability to survive low oxygen conditions for no less than several hours, and zero oxygen conditions for 18 minutes. [100] One of the ways of combatting hypoxia in the brain is decreasing the reliance on oxygen for ATP production, achieved by decreased respiration rates and proton leak.

  8. Oxygen cycle - Wikipedia

    en.wikipedia.org/wiki/Oxygen_cycle

    The oxygen cycle is the biogeochemical cycle of oxygen atoms between different oxidation states in ions, oxides, and molecules through redox reactions within and between the spheres/reservoirs of the planet Earth. [1] The word oxygen in the literature typically refers to the most common oxygen allotrope, elemental/diatomic oxygen (O 2), as it ...

  9. Double bond - Wikipedia

    en.wikipedia.org/wiki/Double_bond

    The double bond is also stronger, 636 kJ mol −1 versus 368 kJ mol −1 but not twice as much as the pi-bond is weaker than the sigma bond due to less effective pi-overlap. In an alternative representation, the double bond results from two overlapping sp 3 orbitals as in a bent bond .