(singular: mitochondrion) Small bacterium-like structures, found in most EUKARYOTE cells, which use OXYGEN and CARBOHYDRATE to fuel the production of ADENOSINE TRIPHOSPHATE (ATP). The mitochondrion is composed of two membranes, an outer and an inner (see MEMBRANE).
The inner membrane is convoluted to produce more surface area and is the site of an ENZYME called ATP SYNTHASE. Within the inner membrane, electrons (see ELECTRON) released during the OXIDATION of carbohydrates are carried by a series of enzymes and cofactors called the ELECTRON TRANSPORT CHAIN and used to drive membrane-bound PROTON pumps, which extrude protons from the matrix to the intermembrane space, against a CONCENTRATION GRADIENT. At sites containing ATP synthase, the energy released when protons flow back across the inner membrane, according to their concentration gradient, is coupled to the synthesis of ATP from adenosine diphosphate and inorganic phosphate. ATP is then transported from the mitochondrion to sites within the cell which break down ATP to fuel cellular reactions.
FIONA M.INGLIS
This is the complete article, containing 161 words
(approx. 1 page at 300 words per page).
