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Enzyme Lab

Enzyme Lab *Only perform under controlled and supervised conditions. For complete lab see link here: https://docs.google.com/document/d/1J... Background: What would happen to your cells if they made a poisonous chemical? You might think that they would die. In fact, your cells are always making poisonous chemicals. They do not die because your cells use enzymes to break down these poisonous chemicals into harmless substances. Enzymes are proteins that speed up the rate of reactions that would otherwise happen more slowly. The enzyme is not altered by the reaction. You have hundreds of different enzymes in each of your cells. In this lab, you will study an enzyme that is found in the cells of many living tissues. The name of the enzyme is catalase; it speeds up a reaction which breaks down hydrogen peroxide, a toxic chemical, into 2 harmless substances--water and oxygen. This reaction is important to cells because hydrogen peroxide (H2O2) is produced as a byproduct of many normal cellular reactions. If the cells did not break down the hydrogen peroxide, they would be poisoned and die. In this lab, you will study the catalase found in potato and liver cells. It might seem strange to use dead cells to study the function of enzymes. This is possible because when a cell dies, the enzymes remain intact and active for several weeks, as long as the tissue is kept refrigerated. Hypothesis: From a hypothesis about the conditions under which an enzyme works best. Be specific! Materials: 1molar HCl solution 1molar NaOH solution Test tubes (6-8) Measuring Pipette Stirring rod 10-ml Graduated cylinder 3% Hydrogen peroxide Straight-edged razor blade glass dish Forceps (tweezers) pH paper Potato Fresh liver Apple, and Carrot Test tube holders, clamps Ice bath Warm water bath Boiling water bath Procedures PART A - Observe Normal Catalase Reaction 1. Label two test tubes 1 and 2. 2. Carefully measure 4 ml of 3% hydrogen peroxide solution and place into a clean test tube. 3. Using forceps and a razor, cut a piece of potato into very small pieces and place a two pieces and into the test tube. Push the potatoes into the hydrogen peroxide with a stirring rod. Observe the bubbles. What gas is being released? 4. Throughout this investigation you will estimate the rate of the reaction (how rapidly the solution bubbles) on a scale of 0-5. Assume that the reaction in step 3 proceeded at a rate of "3". 5. You will also estimate amount of bubbles, also on a scale of 1-5. Assume the bubble level in step 3 is at a level of 4 after a minute or so. 6. Recall that a reaction that absorbs heat is endothermic; a reaction that gives off heat is exothermic. Now, feel the temperature of the test tube with your hand. Has it gotten warmer or colder? Is the reaction endothermic or exothermic? 7. Pour off the liquid (from test tube 1) into a test tube 2, but leave the potato behind. Assuming the reaction is complete. What is this liquid composed of? 8. What do you think would happen if you added more potato to this liquid? 9. Test this and record the reaction rate in Table 1. 10. Add another 4 ml of hydrogen peroxide to the potato remaining in the Test tube 1. Record the reaction rate in Table 1 under the label “Test Tube 1b.” and finish filling out the table. Part B - Concentration of Enzyme -Place 4 ml of hydrogen peroxide in each of the 3 clean test tubes (rinse them well if necessary) and then add each of the four test substances to the tubes. Try to add about the same amount (volume/surface area) of each. As you add each test substance, record the reaction rate and bubble level (0-5) for each tube in Table 2. Part C - What is the Effect of Temperature on Catalase Activity? *CAUTION*: Use a test-tube clamp to move the hot test tubes. -Put a small amount of potato pieces into test tube 1 and leave at room temperature. -Put equal amounts of potato pieces into the bottom of test tube 2. Place this test tube in a boiling water bath for 5 min. -Put equal amounts of potato into test tube 3 and put it in a warm water bath for 5 minutes. -Put equal amounts of potatoes into test tube 4 and put it on ice for 5 minutes. -Put 4 mL of hydrogen peroxide into test tubes 5 and 6 and place 5 in the warm water and 6 in the ice. -Record the temperatures, in °C, of the environments for test tube 1, 2, 3, and 4 in Table 3. -Remove all test tube and place them in a test tube rack. Add 4 mL of hydrogen peroxide to test tubes 1 and 2. Pour the content of test tube 5 into 3 (both from warm water) and the pour the contents of test tube 6 into 4 (both from ice environment). -Record the reaction rate and bubble level for test tubes 1-4 Part D - What is the Effect of pH on Catalase Activity -Using pH paper, determine the pH of your samples -Now add the same amount of potato pieces to each of the test tubes and record the reaction rate and bubble level.