ADENOSINE TRIPHOSPHATE
A denosine triphosphate (ATP) : Biochemistry often feels abstract until you realize that every heartbeat, every thought, and every muscle contraction depends on a single molecule: adenosine triphosphate (ATP) . It is not simply an energy source—it is the universal medium of exchange in cellular economics. Molecular Architecture ATP is composed of three key parts: Adenine : a nitrogenous base Ribose : a five-carbon sugar Three phosphate groups : linked in sequence The energy lies in the phosphoanhydride bonds between the phosphate groups. Hydrolysis of these bonds is energetically favorable because: Negative charges on adjacent phosphates repel each other Inorganic phosphate (Pi) is stabilized by resonance Hydrolysis increases entropy, making the products more stable than ATP itself Hydrolysis and Energy Coupling ATP hydrolysis to ADP + Pi releases about 30.5 kJ/mol under standard conditions. Cells harness this energy by coupling ATP breakdown to reactions that would otherw...