Answer:
Removing a phosphate group from an ATP molecule
Step-by-step explanation:
ATP or Adenosine triphosphate is the energy currency of the cell. It is made of adenine base attached to a ribose sugar and three phosphate groups. The three phosphate groups are bonded via two phosphoanhydride bonds. Both these bonds are high energy bonds. When they are broken, a lot of energy is released. Removal of first phosphate group converts ATP into ADP and energy is released. Removal of second phosphate group converts ADP into AMP and again energy is released but this time it is less than former.