Energy to drive the endergonic regeneration of ATP comes from the exergonic process of cellular respiration. Enzymes A. Enzymes speed up metabolic reactions by lowering energy barriers Free energy change indicates whether a reaction will occur spontaneously, but does not give information about the speed of reaction. Biochemical reactions require enzymes to speed up and control reaction rates. Biological catalysts made of protein. Energy profile of an exergonic reaction 1.
Reaction occurs and energy is released as new bonds form.
In an exergonic reaction the free energy of the products is less than reactants. The breakdown of biological macromolecules is exergonic. These molecules react very slowly at cellular temperatures because they cannot absorb enough thermal energy to reach transition state. Speed up a reaction that would have occurred anyway. The substance an enzyme acts on and makes more reactive.