An Enzyme is a protein that acts as a biological catalyst in most living organisms. Enzymes control the speed in which reactions take place and without them, organisms such as humans would cease to exist (Biology 12, pg.50) .
Every single molecule in existence has some energy and that energy can be classified as kinetic or potential energy. Potential energy is defined as the energy in intermolecular forces or bonds in molecules (Potential Energy, 2015). Kinetic energy of a molecule is the energy a molecule possesses due to the motion of its molecules (Kinetic Energy, 2015). Chemical reactions happen when the kinetic energy of molecules are high so they hit and collide with each other , causing a reaction to happen , although if the kinetic energy of molecules is low then it is quite unlikely for a reaction to take place.
The minimal energy that a reaction needs to take place is called activation energy (Function of Enzymes: Substrate, Active Site & Activation Energy, 2015).
The amount of activation energy required for a reaction to happen varies, although if it is too high, then the reaction will not take place. Also simply relying on activation energy is too slow. In the human body countless reactions are always taking place to stay alive. Furthermore relying on just activation energy for reactions to happen is too slow to keep the human body alive. Enzymes are used as catalysts to lower the amount of activation energy and speed up the rates of reactions which is shown in the work "Activation Energy: Kick starting Chemical Reactions" by Vance Kite.
On Enzymes there is a place called the "active site". These active sites can be seen as locks that can only be specifically opened by a certain key, which is the reactant in this scenario. The reactant that an enzyme binds to is called a substrate. Also there are enzymes that can change the shape of its active site to suit the shape of the substrate it wants to bind to.
