ATP, or Adenosine triphosphate, is a molecule that carries energy and is composed of a base, which in this case is adenine, a ribose sugar and three phosphate groups. The three phosphate groups, which are the alpha, beta and gamma phosphates, are connected to the five-carbon ribose sugar.
The phosphate groups are linked to each other by phosphate bonds, and it is in these bonds that the energy in ATP molecules is held. This chemical energy in ATP is transported within living cells as part of the metabolic process.
ATP is useful in numerous cell processes, including anaerobic respiration, glycolysis, photosynthesis, beta oxidation and the synthesis of macromolecules. It is also used by enzymes in cellular processes such as biosynthetic reactions and cell division.