The primary chemical compound that stores energy in living cells is adenosine triphosphate (ATP). ATP functions as an energy currency, enabling cells to perform various biochemical processes, including muscle contraction, synthesis of macromolecules, and active transport across membranes. ATP is generated through processes like cellular respiration and is quickly replenished as it is depleted in energy-requiring reactions. This dynamic role of ATP is essential for maintaining cellular and overall organismal functions.