Types of bioenergetics reactions

 Types of bioenergetics reactions

There are two types of reactions-

1. Exergonic reaction-An exergonic reaction is a spontaneous chemical reaction that releases energy. It is thermodynamically favored, indexed by a negative value of ΔG (Gibbs free energy). Over the course of a reaction, energy needs to be put in, and this activation energy drives the reactants from a stable state to a highly energetically unstable transition state to a more stable state that is lower in energy (see: reaction coordinate). The reactants are usually complex molecules that are broken into simpler products. The entire reaction is usually catabolic. The release of energy (specifically of Gibbs free energy) is negative (i.e. ΔG < 0) because the energy of the reactants is higher than that of the products.

2. Endergonic reaction-An endergonic reaction is an anabolic chemical reaction that consumes energy. It is the opposite of an exergonic reaction. It has a positive ΔG, for instance because ΔH > 0, which means that it takes more energy to break the bonds of the reactant than the energy of the products offer, i.e. the products have weaker bonds than the reactants. Thus, endergonic reactions are thermodynamically unfavorable and will not occur on their own at constant temperature. Additionally, endergonic reactions are usually anabolic.