Enzyme activity generally increases as temperature increases within an enzyme’s optimal range because an increase in temperature causes an increase in molecular motion. This increase in molecular motion results in the enzyme and its substrate coming into contact with each other more often. At too high a temperature, however, the enzyme will become denatured and no longer be able to function. As the video describes, that is what happens when someone has a high fever.

What do you think happens to enzyme activity as temperature decreases outside an enzyme’s optimal range? Explain your answer in terms of molecular motion.