ATP: Adenosine Triphosphate

Even exergonic, energy-releasing reactions require a small amount of activation energy to proceed. However, consider endergonic reactions, which require much more energy input, because their products have more free energy than the reactants.

Within the cell, from where does the energy to power such reactions come? The answer lies with an energy-supplying molecule scientists called adenosine triphosphate or ATP. This is a small, relatively simple molecule, but within some of its bonds, it contains the potential for a quick burst of energy that can be harnessed to perform cellular work.

Think of this molecule as the cells’ primary energy currency in much the same way that money is the currency that people exchange for things they need. ATP powers the majority of energy-requiring cellular reactions.

ATP is the cell’s primary energy currency. It has an adenosine backbone with three phosphate groups attached.