In the cell, there is a ratio of ATP to ADP, which depends specifically on the needs of the cell at the time of its activity. It is not surprising that a cell consumes so much ATP, and all because it is a universal energy carrier that contains it in its anhydride bonds. ATP is formed by the addition of phosphate to ADP. ATP accompanies many chemical reactions of a cell that could not have occurred without energy. It is because of this need that a huge amount of ATP is utilized.