Question

Explain three reasons, relating to the chemical structure, that ATP is exergonic.

Answer 1

ATP hydrolysis is the catabolic reaction process in which chemical energy that has been stored in the high energy phosphoanhydride bonds in adenosine triphosphate (ATP) is released by splitting these bonds.

E.g. In muscles by producing work in the form of mechanical energy.

ATP hydrolysis is the final link between the energy derived from food or sunlight and useful work such as muscle contraction.

Hydrolysis of the phosphate group in ATP is especially exergonic because the resulting orthophosphate group is greatly stabilised by multiple resonance structure, making the products(ATP and Pi) much lover in energy than the reactant (ATP).

The negative charge density associated with the three adjacent phosphate units of ATP also destabilizes the molecule, making it higher in energy.

Hydrolysis relieves some of these electrostatic repulsion, liberating useful energy in the process by causing conformational charges in enzymes structure.

In human approximately 60 % of the energy released from the hydrolysis of ATP produces metabolic heat rather than fuel the actual reaction taking place.

Summary: Hydrolysis of the phosphate group in ATP is especially exergonic because the resulting orthophosphate group is greatly stabilised by multiple resonance structure, making the products(ATP and Pi) much lover in energy than the reactant (ATP).