ATP can be represented by this hamster wheel, since energy is expelled when running on it. ATP, or adenosine triphosphate, is the energy currency of the cell. This compound consists of an adenosine molecule bonded to three phosphate groups. Energy is released when a phosphate linkage is broken; this is because of hydrolysis. ATP is present in every cell, and it is responsible for storing energy to be involved in cellular metabolism. Once ATP is used, it can be recycled by adding a new phosphate to the existing ADP. In animals, ATP is produced in the mitochondria.