Grivell, Les A. Afdeling Moleculaire Biologie, Laboratorium voor Biochemie, Universiteit van Amsterdam, The Netherlands.
Last reviewed:May 2018
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- Energy conservation
- Mitochondrial genetic systems
- Mammalian mtDNA
- Links to Primary Literature
- Additional Readings
Specialized compartments (organelles) of almost all eukaryotic cells that are necessary for cellular respiration and energy production. Mitochondria (Fig. 1) are double-membrane-bound cytoplasmic organelles that occur in most eukaryotic (nucleated) cells that use oxygen. Often called the powerhouses of the cell, mitochondria (the singular form is mitochondrion) are responsible for energy generation by the coupled processes of electron transport and oxidative phosphorylation. In these processes, electrons produced during the oxidation of simple organic compounds are passed along a chain of four membrane-bound enzymes (the electron transport or respiratory chain), finally reacting with and reducing molecular oxygen to water. The movement of the electrons releases energy that is used to build a gradient of protons across the membrane in which the electron transport chain is situated. Like a stream of water that drives the turbines in a hydroelectric plant, these protons flow back through adenosine triphosphate (ATP) synthase, which is a membrane-bound enzyme that acts as a molecular turbine. Rotation of part of the ATP synthase results in storage of energy in the form of ATP, which is the universal energy currency of the cell. See also: Adenosine triphosphate (ATP); Biological oxidation; Cell (biology); Cell biology; Cell organization; Eukaryota; Oxygen
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