either of the two saclike respiratory organs in the thorax of humans and the higher vertebrates. 2. an analogous organ in certain invertebrates, as arachnids or terrestrial gastropods. Idioms. 3. at the top of one's lungs, as loudly as possible; with full voice: The baby cried at the top of his lungs.
Mitochondria are the energy factories of the cells. The energy currency for the work that animals must do is the energy-rich molecule adenosine triphosphate (ATP). The ATP is produced in the mitochondria using energy stored in food. Just as the chloroplasts in plants act as sugar factories for the supply of ordered molecules to the plant, the mitochondria in animals and plants act to produce the ordered ATP molecules as the energy supply for the processes of life.
When ATP levels are high in the cell, the cell no longer needs metabolic energy production to occur. In this case, PFK's activity is inhibited by allosteric regulation by ATP itself, closing the valve on the flow of carbohydrates through glycolysis.Source(s): http://www.wiley.com/legacy/college/boye...he majority of the ATP in the cell is produced by the Electron Transport System located in the mitochondrion. Under aerobic conditions, the pyruvate produced in the glycolystic pathway enters the mitochondrion and is converted to acetyl CoA by the enzyme pyruvate dehydrogenase.