Adenosine triphosphate (ATP) functions as the energy currency of biological systems because its structure — an adenosine moiety (adenine joined to a ribose) bonded to a chain of three phosphoryl groups — holds electrons in a comparatively high-energy configuration within the terminal phosphoanhydride bonds. Hydrolysis, the reaction of ATP with water, cleaves the terminal phosphoryl group to yield adenosine diphosphate (ADP) and inorganic phosphate, allowing those electrons to settle into a lower-energy state and releasing energy; the reverse reaction, phosphorylating ADP back to ATP, consumes energy and therefore stores it. This concept belongs to biochemistry and cellular metabolism, and it establishes the general principle of a rechargeable chemical intermediate that couples energy-releasing processes to energy-requiring ones throughout the cell.
Adenosine triphosphate (ATP) functions as the energy currency of biological systems because its structure — an adenosine moiety (adenine joined to a ribose) bonded to a chain of three phosphoryl grou…