ATP is short for adenosine triphosphate, it is a modified RNA molecule used as an immediate energy source.
It is made of:
- adenine (nitrogenous base)
- ribose, and;
- three phosphate groups.
When the terminal phosphate is removed from ATP (when it is used), the last phosphate group gets removed, so the molecule only contains two phosphate groups.
- At this point, it is called adenosine diphosphate.