Explain how enzymes speed up chemical reactions and how they are denatured.

Enzymes speed up chemical reactions by lowering the activation energy, which provides an alternative pathway, making it easier to reach the transition state. Enzymes are denatured by changes in temperature and pH. This causes the Hydrogen bonds to break which changes the tertiary structure of the enzyme. The shape of the active site is changed so the substrate no longer fits and therefore the enzyme-substrate complex cannot form.