ATP

Adenosine triphosphate or ATP is the energy-carrying molecule within all living cells. Without it our muscles would not work, our nerves would not feel, we could not digest food, sperm could not swim to fertilize eggs and life as we know it would be impossible. Yet this vital molecule works in a very simple and fascinating way.

It stores energy in a sort of molecular spring, like a toy gun, ready to fire little bullets and release its energy, or pass it on to another molecule.

Here we show the structure of ATP. It consists of three main parts: adenine, ribose and triphosphate. So which part is which?

You can see the adenine which gives the ‘adeno' part of the name. The ribose gives the ‘sine' part. The three phosphorus (P) atoms give the ‘phosphate' part and the ‘tri' is used because there are three of them. Altogether that makes adenosine triphosphate, but we'll just call it ATP.

The three phosphates in ATP are acids and each loses a proton when in water. The protons take away positive electric charge and leave negative charge on the phosphates.

It is the electrical repulsion between these three phosphate molecules that stores energy. We explain how this in more detail on the phosphate page.

This force of repulsion is like a coiled spring ready to fire. See the ADP page to find out what happens when it does!