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( Mitochondrion)
In cell biology, a mitochondrion (plural mitochondria) is a membrane-enclosed organelle found in most eukaryotic cells.[1] These organelles range from 1–10&_160;micrometers (µm) in size. Mitochondria are sometimes described as "cellular power plants" 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 a range of other processes, such as signaling, cellular differentiation, cell death, as well as the control of the cell cycle and cell growth.[2] Mitochondria have been implicated in several human diseases, including mental disorders,[3] cardiac dysfunction,[4] and may play a role in the aging process. The word mitochondrion comes from the Greek µ?t?? or mitos, thread + ???d???? or khondrion, granule. Their ancestry is not fully understood, but, according to the endosymbiotic theory, mitochondria are descended from ancient bacteria, which were engulfed by the ancestors of eukaryotic cells more than a billion years ago. Several characteristics make mitochondria unique. The number of mitochondria in a cell varies widely by organism and tissue type. Many cells have only a single mitochondrion, whereas others can contain several thousand mitochondria.[5][6] The organelle is composed of compartments that carry out specialized functions. These compartments or regions include the outer membrane, the intermembrane space, the inner membrane, and the cristae and matrix. Mitochondrial proteins vary depending on the tissues and species. In human, 615 distinct types of proteins were identified from cardiac mitochondria;[7] whereas in murine, 940 proteins encoded by distinct genes were reported.[8] The mitochondrial proteome is thought to be dynamically regulated.[9] Although most of a cell's DNA is contained in the cell nucleus, the mitochondrion has its own independent genome. Further, its DNA shows substantial similarity to bacterial genomes.[10] A mitochondrion contains outer and inner membranes composed of phospholipid bilayers and proteins.[5] The two membranes, however, have different properties. Because of this double-membraned organization, there are five distinct compartments within the mitochondrion. There is the outer mitochondrial membrane, the intermembrane space (the space between the outer and inner membranes), the inner mitochondrial membrane, the cristae space (formed by infoldings of the inner membrane), and the matrix (space within the inner membrane). The outer mitochondrial membrane, which encloses the entire organelle, has a protein-to-phospholipid ratio similar to that of the eukaryotic plasma membrane (about 11 by weight). It contains large numbers of integral proteins called porins. These porins form channels that allow molecules 5000&_160;Daltons or less in molecular weight to freely diffuse from one side of the membrane to the other.[5] Larger proteins can also enter the mitochondrion if a signaling sequence at their N-terminus binds to a large multisubunit protein called translocase of the outer membrane, which then actively moves them across the membrane.[11] Disruption of the outer membrane permits proteins in the intermembrane space to leak into the cytosol, leading to certain cell death.[12]
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Mitochondrion Subcategories
Mitochondrion Articles
The Small, Fat Burning Powerhouse in The Body - The Mitochondrion by Bryan Miller
So you want to lose your gut, hips, thighs, and wiggly area’s, eh? Your belly fat is getting to be an nuisance, not just because of looks, but because you just feel low about yourself. I understand that, been there myself; still struggle with it. But...
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