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Automatic Zoom View as Te ENZYME ACTIVITY PART B 2- Lab 5: Factors Affecting Enzyme Activity Protocol In this exercise, you will test the effects of extreme heat (100 °C) and low pH (very acidic) on enzyme activity (i.e., function). To test the pH of common household items, you will be using pH paper or creating pH sensitive paper by microwaving red cabbage leaves. Think about whether or not this experiment has a negative and/or a positive control. A negative control is when we know before we do the experiment that it should not work since there is something lacking. An experiment would have a positive control if we know before we do the experiment that it should work since everything needed for the experiment is included. In this experiment, a negative control should test negative for enzyme activity (catechol will be present). The positive control should produce benzoquinone; therefore, there should be browning. It is considered a positive control because it will test positive for full potential enzyme activity (i.e., the enzyme functioned). An experimental group is different from the negative and positive controls. The experimental group is a group where we are testing if something will work or not. We have a hypothesis beforehand but we do not know for certain whether or not it will work. The negative and positive controls are different. We know that something is missing for the negative control or all of the reagents are present for the positive control.
DIRECTIONS Enzyme Denaturation by pH 1. If you were unable to purchase pH paper, you can make pH paper to be able to identify common acids and bases around the house. (If you have pH paper, skip to step 8) 2. Blend or grate ½ of a red cabbage head. If you don't have a blender or grater, then chop up cabbage using a knife. 3. Place the cabbage shreds in a bowl and microwave until steaming hot (Microwave times will vary between 1 and 3 minutes). If you don't have a microwave, you can cook the cabbage on the stove. The goal is to cook the cabbage enough that the plant cells burst and release the pigment inside them. 4. Pour the cabbage juice through a mesh strainer or colander and capture the liquid. Throw away the cabbage shreds. 5. Pour the strained cabbage juice through a coffee filter and capture the fluid. 6. Cut a coffee filter into 1-inch squares and soak them in the cabbage juice for 5 minutes. Allow them to dry. 7. The paper will change colors depending on the pH of the liquid placed on it. Neutral pH (7) will not change the color, though it will make the color seem darker due to wetness. Weak bases (9-10) will give a blue color and strong bases (12-14) will give a green color. Weak acids (3-5) will give a violet or red color and strong acids (1-2) will give a pink color. 8. Place a drop of water, a drop of lemon juice, a drop of white vinegar, and a drop of ammonia onto a separate pH test paper. Determine the pH of each solution.
3- Lab 5: Factors Affecting Enzyme Activity Protocol 9. Cut 4 fresh slices of apple. Soak one slice of apple in each of the four solutions for 5 minutes. 10. Pull the slices out of the solutions and set them on a plate. Observe the slices every 30 minutes for 2 hours and record your results. Enzyme Denaturation by Temperature 1. Cut one fresh slice of apple and boil for10 minutes. 2. Cut another fresh slice of apple (room temperature) and place on a plate with boiled apple slice. 3. Put a fresh apple slice in the refrigerator and a fresh apple slice in the freezer. 4. Observe the slices every 30 minutes for 2 hours and record your results.
ENZYME ACTIVITY PART B Answer the following questions about enzymes and proteins. 5. Do proteins lose their tertiary structure when they are boiled? Why or why not? (1 point) 6. Do proteins lose their primary structure when they are boiled? Why or why not? (1 point)
Record your results in Table 1 below (1 point). pH of Solution Solution Effect of Solution (Browning or no browning) Water Ammonia Vinegar Lemon Juice 7. Based on your results above, which apple slice contained an active enzyme (i.e., the enzyme functioned)? What is your evidence? (1 point) I 8. Was water a positive or a negative control or an experimental group? (1 point) 9. What was the effect of changing the temperature on the catecholase reaction? Did the reactions still occur? (1 point)