Final answer:
When the 3rd phosphate group is removed from ATP, energy is released, converting ATP to ADP and a free phosphate group. This process is a core component of the cellular energy transfer system and is critical for numerous cellular functions.
Step-by-step explanation:
When the 3rd phosphate is removed from ATP (adenosine triphosphate), energy is released. This process of removing a phosphate group is called dephosphorylation. ATP is converted into ADP (adenosine diphosphate) and a free phosphate group. The bonds holding the phosphates in ATP contain a lot of stored energy, and when these bonds are broken, the energy is freed up and can be used for various cellular processes.
The release of this energy from ATP happens through a reaction often represented as ATP + H₂O → ADP + phosphate. In terms of cellular metabolism, ATP serves as a kind of energy currency. It stores and provides energy for many biochemical cellular processes, being used up during energy-consuming processes and regenerated from ADP during energy-releasing processes.