Catalysts accelerate chemical reactions that otherwise proceed slowly. The enzyme called catalase is a catalyst. It exists in plant and animal cells and breaks down hydrogen peroxide, H2O2, which is a byproduct of metabolism that is toxic if it accumulates in a cell. Catalase, like most enzymes, is sensitive to the conditions in which it operates. Under favorable conditions, the reaction occurs very fast. MVHS offers three activities that explore the effects of temperature and pH on enzyme reaction rates. In the first activity, the students build a computer model in a systems programming language. The enzyme reaction rate activity allows students to simulate the effects of variables such as temperature and pH on the reaction rate of the enzyme catalase. This computer simulation is best used after the students have done a wet lab experiment. The value of the simulation is that it requires the students to interpret and analyze the graphical representation of data and it enables the running of mutiple experiments in a short amount of time. The second activity is a web-based simulation derived from the systems model. The main factors that influence enzyme-catalyzed reactions are temperature, pH, enzyme concentration, and substrate concentration. The purpose of this simulation is to discover the optimal conditions for a fast reaction rate. The third activity provides a complete set of lessons for the teaching of enzyme reaction rates. Each module is organized according to the 5E guidelines. In Module 3, either activity described above may be used as the extension.

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