Enzymes as Biological Catalysts
- Enzymes are biological catalysts
- ‘Biological’ because they function in living systems
- ‘Catalysts’ because they speed up the rate of chemical reactions without being used up or changed
Graph to Show How Enzymes Lower Activation Energy
The activation energy of a chemical reaction is lowered by the presence of a catalyst (ie. an enzyme)
Enzymes work by lowering the activation energy of a reaction
- All chemical reactions are associated with energy changes
- For a reaction to proceed there must be enough activation energy
- Activation energy is the amount of energy needed by the substrate to become just unstable enough for a reaction to occur and for products to be formed
- Enzymes speed up chemical reactions because they influence the stability of bonds in the reactants
- The destabilization of bonds in the substrate makes it more reactive
- Enzymes work by lowering the activation energy of a reaction and in doing so they provide an alternative energy pathway
Exam Tip
Don't forget that enzymes are proteins and so anything that could denature a protein, extremes of heat, temperature, pH etc. would also denature an enzyme.
