ATPs are the power cell of a cell. Just like a cell, they need to be charged before they can deliver power.
ATP or the Adenosine Triphosphate is a complex molecule containing a Adenine nitrogen base, a ribose sugar and three phosphates being attached with each other in a chain. Adenosine Triphosphate is the power currency of a cell. It just acts like a rechargeable battery. The metabolic and physiological processes of a cell that needs energy, involves the hydrolysis of ATP into ADP and Pi which are Adenosine Diphosphate and Inorganic phosphate respectively.
Now the ATP is discharged and needs to be charged. So the ADPs are charged into ATPs by different processes of respiration like Glycolysis, Kreb's Cycle, Electron Transport Chain etc.
Both the hydrolysis and the condensation of ATP makes the ATP cycle.
