ACTIVATION ENERGY [ENZYMES]

=Enzymes and Activation Energy= [image:http://i.imgur.com/HBmQI4B.gif] All chemical reactions require some energy input to begin. The amount of energy needed before a reaction will proceed on its own is called activation energy. Energy is needed to break existing bonds before new bonds can be formed. The formation of new bonds may release more energy than was needed to break the original bonds. Even though there may be a net (overall) release of energy, the need for activation energy can act as a barrier to the chemical reaction occurring. [image:http://i.imgur.com/2vqJkwp.png?1] Enzymes lower the barriers that normally prevent chemical reactions from occurring by decreasing the required activation energy. The the initial rise in energy seen in the graph (left) is the energy input needed before the reaction will occur (activation energy). The subsequent drop in energy is the energy released by the reaction. You can see that the reaction requires less activation energy when an enzyme is present (red line). This is why the addition of an enzyme allows a reaction to proceed at a much faster rate. ==How Enzymes Reduce Activation Energy== [image:http://i.imgur.com/nSt14zz.gif] In order for a chemical reaction to occur the reactants must collide with sufficient ''kinetic energy'' and a specific ''orientation''. The reactants must collide with enough energy to break existing bonds. This is the activation energy that is required for the reaction to begin. However, less energy is needed if the reactants collide at the right angle. [image:http://i.imgur.com/xVUpstU.gif] An enzyme reduces the activation energy needed for a reaction to occur by providing the reactants with better orientation, thereby increasing the frequency of successful collisions and the rate of reaction.