What does ATP become after losing a phosphate group?

When ATP (adenosine triphosphate) loses a phosphate group, it is hydrolyzed into ADP (adenosine diphosphate) and an inorganic phosphate. This process involves the breaking of a high-energy bond between the second and third phosphate groups of ATP, which releases energy that can be harnessed by the cell for various metabolic processes. ADP, which contains only two phosphate groups, represents a lower energy form compared to ATP.

The transformation from ATP to ADP is a critical reaction in cellular energy metabolism, playing a pivotal role in both photosynthesis and cellular respiration. This change signifies a loss of energy potential, and ADP can later be converted back into ATP through phosphorylation, thus continuing the energy cycle within cells. The other choices do not represent the immediate product of ATP when it loses a phosphate; for instance, AMP (adenosine monophosphate) is formed only when ADP loses another phosphate group, and ATP-2 and adenosine do not accurately depict the resultant product of the loss of a phosphate group.