ATP
Definition
The cell's energy currency: a molecule whose high-energy phosphate bonds power nearly everything cells do.
Symbol: ·
Technical definition
Adenosine triphosphate (ATP) is the primary energy carrier in cells. Hydrolysis of its terminal phosphate (ATP -> ADP + Pi, about -30.5 kJ/mol) releases energy that drives energy-requiring processes, with ATP regenerated by cellular respiration and photosynthesis.
Example
Muscle contraction burns ATP directly. Sprinting muscles can deplete their ATP in seconds, which is why rapid regeneration matters.
Common confusion
The high-energy bond is not magic. The energy comes from the overall hydrolysis reaction being favorable (stable products, resonance, solvation), not from the bond itself containing bottled-up energy.