Enzymes lower the activation energy necessary to transform a reactant into a product. On the left is a reaction that is not catalyzed by an enzyme (red), and on the right is one that is (green).

Activation energy is the minimum energy needed for ‘successful collisions’ where atoms within the reactants rearrange to form products. It can be represented on an energy level diagram.

Save guides, add subjects and pick up where you left off with your BBC account. starts at the energy of the reactants is equal to the difference in energy between the top of the 'hump' and the ...