The rate of reaction does not solely depend on the free energy difference between the initial and final states, but instead on the actual path through which the reactants are transformed into products. Without these catalysts, simple tasks that occur within living organisms cannot take place at a rate beneficial to the species. The enzymes increase the rate of reaction without effecting the reactions difference in free energy. Natural mechanisms such as the digestion of food, the conservation and transformation of chemical energy, and the construction of cellular macromolecules from smaller precursors are all supported with the use of enzymes. In fact, if a living organism is deficient in a particular enzyme, it could result in serious diseases and possibly death.
Enzymes also act in industrial and medical applications.
The fermenting of wine, leavening of bread, the curdling of cheese, and the brewing of beer have been practiced for centuries, but it wasn't until recently that all these processes have been discovered to be possible with the use of enzymes. Enzymes accelerate biochemical reactions by physically interacting with the reactants and products to provide a more favorable pathway for the transformation of one to the other. They increase the rates of reactions by increasing the probability that the reactant can interact properly. As D G is harvested, stored, or used to perform cellular work, it can be transferred to other molecules. It can be transferred into heat, electrical work, or mechanical work depending on the needs of the organism.