Here's a breakdown:
* ADP stands for adenosine diphosphate. It has two phosphate groups attached to it.
* ATP stands for adenosine triphosphate. It has three phosphate groups attached to it.
The process of adding a phosphate group to ADP is called phosphorylation. This process requires energy, which is often obtained from the breakdown of food molecules. ATP is considered the "energy currency" of cells because it readily releases energy when its phosphate bond is broken, allowing cells to perform essential functions.
