Final answer:
A denatured enzyme cannot accelerate a chemical reaction due to the loss of its three-dimensional structure and active site configuration, typically caused by high temperatures or extreme pH levels that break the bonds essential for enzyme function.
Step-by-step explanation:
A denatured enzyme is unable to speed up a chemical reaction because its three-dimensional structure, which is essential for its function, has been altered. Enzymes operate based on the precise fit between their active site and the substrate; this is often depicted as a 'lock and key' model. Denaturation disrupts the chemical bonds within the active site, making it less suited to bind substrates effectively. Factors like high temperature and extreme pH values can lead to denaturation. For instance, while increasing temperature can initially hasten reaction rates, beyond an enzyme's optimal temperature range, such an increase can denature the enzyme. At extreme temperatures, the added thermal energy breaks the weak bonds that maintain the enzyme's specific shape, leading to loss of functionality. Moreover, while enzymes work well within a certain pH range, exposure to highly acidic or basic environments can also result in denaturation.