Adenosine triphosphate (ATP) is the energy molecule used by all cells to do work. It is a nucleotide consisting of adenine, a 5-carbon sugar, and 3 phosphate groups. ATP is able to store and transport chemical energy within cells. The LAST TWO phosphate groups are joined by ONE HIGH-ENERGY bond. When this bond is broken, energy is released for cells to use and ADP forms. Enzymes help to break and reform these high-energy bonds.