Adenosine Triphosphate (ATP) is an organic molecule that stores and releases energy for use in celullar processes. It is the chief source of energy in skeletal muscle and fuels all human movement. ATP can be thought of as the "energy currency" of cells. No cell uses the energy from glucose breakdown directly, the energy is harnessed in ATP.
A molecule of ATP consist of adenine, which contains nitrogen; and a five-carbon sugar ribose. These together are called adenosine. Attached to the ribose end is a string of three phosphate groups. The bonds of this molecule are very unstable since all three phosphates are negatively charged, thus repelling one another.
Many different enzymes can strip off the outer phosphate group very easily. When one phosphate groups is removed by hydrolosis, a more stable molecule, adenosine diphosphate (ADP). Like all such changes from unstable to stable configurations, this results in the release of energy. The stripping of a phosphate group from ATP releases plenty of energy that can be used to do cellular work like breaking apart other molecules, transporting things to and and from cells, and, of course, triggering muscle contractions.
Once a molecule of ATP has been "used" by having one phosphate stripped off, the resulting ADP is ready to be recycled. When glucose and fat are broken down, some of their energy is used to add a phosphate to the ADP, which is called phosphorylation.
This page created 06 Sep 2011 14:30
Last updated 02 Mar 2016 18:21