How are atp and adp used in energy transfer within a cell?

Adenosine triphosphate (ATP) is a biological molecule with a ribose sugar, Adenine (nitrogenous base) and phosphate component. It is the major storage molecule of energy in living cells as cells can only make use of energy in the ATP form. This energy is released when needed by cells, by breaking the bonds that hold one of the phosphate groups.

The ATP molecule loses one phosphate group, making energy readily available for the target cell or pathway. The ATP becomes an Adenine diphosphate (ADP) molecule in the process.

In turn, if energy is needed to be stored, an inorganic phosphate is added to ADP to form ATP catalyzed by a synthetase enzyy.