Mitochondrion

The mitochondrion (plural mitochondria) is a double membrane-bound organelle found in most eukaryotic cells. The word mitochondrion comes from the Greek μίτος, mitos, i.e. "thread", and χονδρίον—, chondrion, i.e. "granule" or "grain-like".

Mitochondria are commonly between 0.75 and 3μm in diameter but vary considerably in size and structure. Unless specifically stained, they are not visible. Mitochondria have been described as "the powerhouse of the cell" because they generate most of the cell's supply of adenosine triphosphate (ATP), used as a source of chemical energy. In addition to supplying cellular energy, mitochondria are involved in other tasks, such as signaling, cellular differentiation, and cell death, as well as maintaining control of the cell cycle and cell growth. Mitochondria have been implicated in several human diseases, including mitochondrial disorders, cardiac dysfunction, and heart failure. In 2014, a study including ten children diagnosed with severe autism suggests that autism may be correlated with mitochondrial defects.