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AP Bio Lab # 13 Enzyme Activity Pre-Lab

AP Bio Lab # 13 Enzyme Activity Pre-Lab. Before doing this lab, you should understand :. The general functions and activities of enzymes The relationship between the structure and function of enzymes The concept of initial reaction rates of enzymes

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AP Bio Lab # 13 Enzyme Activity Pre-Lab

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  1. AP Bio Lab # 13Enzyme ActivityPre-Lab

  2. Before doing this lab, you should understand: • The general functions and activities of enzymes • The relationship between the structure and function of enzymes • The concept of initial reaction rates of enzymes • How the concept of free energy relates to enzyme activity (view graph) • That changes in temperature, pH, enzyme concentration, and substrate concentration can affect the initial reaction rates of enzyme-catalyzed reactions (view graph)

  3. Learning Objectives • Students will use the catalase reaction to demonstrate different variables’ effect on enzyme activity: • such as temperature and the presence of catalase. • Students will observe the reaction of hydrogen peroxide and catalase: • establish a baseline determining the amount of hydrogen peroxide in a 1.5% solution, • Determine the rate of spontaneous conversion of hydrogen peroxide to water and oxygen • determine the rate of hydrogen peroxide decomposition by enzyme catalysis.

  4. Background Info • In this experiment, we will be using the enzyme catalase. • found inside peroxisomes in almost all organisms. • catalysesthe breakdown of hydrogen peroxide to water and oxygen. • Without this enzyme, hydrogen peroxide would destroy our cells because it is a toxic metabolic waste product of aerobic respiration. 2 H2O2 2 H2O + O2 (gas)

  5. Background Info Cont: • Reaction is spontaneous (will occur naturally), but very slowly. • If catalase is boiled, it will become denatured and will no longer function to break down hydrogen peroxide. • The rate of this reaction will decrease as the concentration of hydrogen peroxide (the substrate) decreases.

  6. Safety • Read all instructions before beginning lab. • Wear personal protective eyewear (PPE) at all times, included during clean-up. • Wear gloves and aprons, will stain clothes! • Wash hands before leaving lab.

  7. Show lab video

  8. Part A: Demo (3 parts)Mix Hydrogen Peroxide (H2O2) + Catalase

  9. The General Procedure • H2SO4 stops the reaction! Measure using Potassium Permanganate Drops

  10. Part B: Establishing a Baseline – Determining the Amount of Hydrogen Peroxide (H2O2) in a 1.5% solution • Add Hydrogen Peroxide (H2O2) • Add Water (control) • Add Sulfuric Acid (H2SO4) • Titrate with Potassium Permanganate (KMnO4) • Amount of (KMnO4) used to titrate is proportional to amount of (H2O2) present in the solution

  11. Part C: Demo Overnight • Control Group: Do NOT add any catalase enzyme, and measure rate of Hydrogen Peroxide Spontaneous Decomposition

  12. Part D: Rate of Hydrogen Peroxide Decomposition by Enzyme Catalysis • After you get your baseline • Add Hydrogen Peroxide (H2O2) and Catalase solution, swirl for 10 seconds • Add Sulfuric Acid (H2SO4) to stop reaction • Titrate with Potassium Permanganate (KMnO4) • Repeat for 30, 60, 120, & 180 seconds ***Do in reverse order to improve your accuracy, start with 180, 120, 60, 30, 10***

  13. 2. Swirl, if solution turns back clear, continue adding one drop at a time 3. Stop adding drops when solution remains a pinkish – yellowish color, measure & record amount of KMnO4 used. 1. Start Adding one drop at a time

  14. Data • Record your data in the appropriate data table as you complete the lab.

  15. Conclusion Analysis Questions

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