How does mitochondria generate energy ?

Question

How does mitochondria generate energy ?

Answer 1

Mitochondria perform "aerobic respiration," a process that generates the energy molecule ATP from nutrient molecules using oxygen. This process is critical in that ATP constitutes one of the body's principal usable energy reservoirs. Three key components of aerobic respiration are 1) glycolysis, 2) the Kreb's cycle, and 3) the electron transport chain (ETC). In glycolysis, one molecule of glucose is split into two pyruvate molecules, generating 2ATP and 2NADH molecules. Pyruvate is then converted into acetyl-CoA (acetyl coenzyme A), which enters the Kreb's cycle to generate 1 ATP, 1 FADH2, and 3 NADH per acetyl-CoA. The NADH and FADH2 molecules serve as "electron carriers" by transferring electrons derived from glycolysis and the Kreb's cycle into the ETC. In the ETC, proteins in the inner membrane use these electrons to create a pH gradient across the inner membrane; the membrane proteins pump protons from the inner matrix into the intermembrane space. This gradient serves as an energy reservoir that drives the creation of ATP as protons are pumped back into the inner matrix through a membrane protein called "ATP-synthase."  

Answer 2

In cell biology, a mitochondrion (plural mitochondria) is a membrane-enclosed organelle found in most eukaryotic cells. These organelles range from 1–10 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. Mitochondria have been implicated in several human diseases, including mental disorders, cardiac dysfunction, and may play a role in the aging process. The word mitochondrion comes from the Greek μίτος or mitos, thread + χονδρίον 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.

Answer 3

Most of the energy is produced by pumping H+ ions across a membrane.  Then enzymes are used to capture the energy of the electrons trying to equalize the electric charge like in a hydrogen fuel cell.  The difference is that in the mitochondria the enzyme uses the electrical potential to produce ATP.  It is really more complicated than that but wikipedia has a wonderful description if you wanted to get exactly what happens.

http://en.wikipedia.org/wiki/Mitochondri...