Question

Describe the relationship between ATP and ADP and the importance of this relationship within a cell. (I know Adenosine TRI phosphate (ATP) is just like adenosine DI phosphate (ADP), except that ATP has a third phosphate group stuck on the end of the molecule.. but what is the relationship with in the cell?)

Answer 1

ATP has 3 phosphate bonds. These bond are highly energetic (ATP is more like compressed spring ready to release anytime) because whenever there is need for some energy in the cell, the 1st phosphate readily breaks with the release of a large amount of energy, converts into less energetic ADP and this energy is used in performing different activities in the cell, thus maintaining cell's physiology. ADP in certain cases may release another phosphate converting into AMP but that's very rare.
The ADP or AMP now needs to be converted back into ATP because of the cell's constant need for energy, and this happens in Mitochondria. This is the reason why Mitochondria is called the "Power House" of the cell.