Understand the role of enzymes as biological catalysts in metabolic reactions.
We will take C6H12O6 and the presence of O2 and convert this to a release of energy+CO2+H2O
In the beginning of the reaction the glucose and oxygen will place in around the middle of our graph in which the y axis indicates the energy of the substrate. The bottom line represents the energy released and the energy release is indicated by the energy drop in the graph.
However, without an enzyme to break down glucose to carbon dioxide and water we will have to input energy in order to break the bonds in glucose just like the process of combustion. So initially we will need to add energy [Energy of Activation] which could be in the form of heat or extreme ph, however, they are both damaging to human cells; our biological system has found a way to overcome the energy of activation - through enzymes.
The enzymes would combine with the glucose and oxygen to form an activated complex weakening the structure without the need of heat or extreme ph and overcome the energy of activation (shown in red line). The role of the enzyme here is to reduce the energy of activation, so we can say that it makes the reaction occur more easily or faster.