mitochondrion

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mitochondrion An oval, or occasionally round or thread-shaped, organelle, whose length averages 2μm, and which occurs in large numbers in the cytoplasm of eukaryotic cells. It is a double-membrane-bound structure in which the inner membrane is thrown into folds (the cristae) that penetrate the inner matrix to varying depths. It is a semi-autonomous organelle containing its own DNA and ribosomes, and reproducing by binary fission. It is the major site of ATP production and thus of oxygen consumption in cells, and houses the enzymes involved in the citric acid cycle and in oxidative phosphorylation.

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