What distinguishes exergonic reactions from endergonic reactions?

Exergonic reactions are characterized by their ability to release energy during the process, which often occurs spontaneously. This energy release is associated with the breakdown of molecules or the transformation of energy from one form to another. In contrast, endergonic reactions require an input of energy for the reaction to proceed, as they involve the synthesis or building of more complex molecules. The distinction lies in the direction of energy flow: exergonic reactions lead to a decrease in free energy within the system, while endergonic reactions result in an increase in free energy, necessitating energy absorption from the surroundings to drive the reaction forward.

This fundamental difference in energy dynamics explains why exergonic reactions can proceed without additional energy input, while endergonic reactions cannot. This understanding is critical in biological systems, where cellular metabolism relies on the interplay between these two types of reactions to maintain life processes.