The purpose of this video lesson is to expand the student’s knowledge about enzymes by introducing the antioxidant enzymes that are intimately involved in the prevention of cellular damage and eventual slowing of the aging process and prevention of several diseases. Students will learn that natural antioxidant enzymes are manufactured in the body and provide an important defense against free radicals. The topic of free radical action is introduced, covering how they are constantly generated in living cells both by "accidents of chemistry" and also by specific metabolic processes. Prerequisite knowledge for this lesson includes a familiarity with enzymes and their role as catalysts in mediating and speeding a specific chemical reaction in the body, as well as an understanding of the oxidation process. This lesson can be completed in 30 minutes, and materials needed include a blackboard and fresh fruits and vegetables. In-class activities for the breaks between video segments include small group problem solving and discussion around the material presented.