Enzymes Lab Worksheet (M/C #4)

Transcription

1 Enzymes Lab Worksheet (M/C #4) NAME: Ex. 4-1: EXPERIMENTAL METHOD AND THE ACTION OF CATECHOL OXIDASE What question are you addressing in this experiment? Propose a testable hypothesis for the presence or absence of catechol oxidase in potato extract. Predict the result of this experiment (if/then). What is the purpose of each of the three test tubes? Which is the control tube (think in terms of the independent variable)? Why is a second control tube necessary? Design a table below in which you will record your results: Ex. 4-2: INHIBITION OF CATECHOL OXIDASE Propose a question about the catechol oxidase inhibitor PTU. Hypothesize about the nature of inhibition by PTU (i.e., competitive or non-competitive). Which test tube is the control? 73

2 Why was the concentration of the catechol increased in test tube 2? It is best to add the potato extract to the test tubes last. Why is this? Design a table and record your results below: One member of your team is not convinced you have adequately tested your hypothesis. How could you expand this experiment to provide additional evidence to strengthen your conclusion? Ex. 4-3: INFLUENCE OF CONCENTRATION, ph, AND TEMPERATURE ON THE ACTIVITY OF AMYLASE Experiment A: The Influence of Enzyme Concentration on the Rate of Starch Digestion Formulate a question about enzyme concentration and reaction rate. Hypothesize about the effect of changing enzyme concentration on the time of starch disappearance. Time of starch disappearance in different concentrations of the enzyme amylase (do not exceed 4 min): Tube % Amylase Time of Starch Disappearance (sec)

3 The independent variable is and should be plotted on the axis. The dependent variable is and should be plotted on the axis. Experiment B: The Effect of ph on Amylase Activity Formulate a question about ph and reaction rate. Hypothesize about the time of starch disappearance at various ph levels. Time of starch disappearance at different ph values for the enzyme amylase (do not exceed 4 min): Tube ph Time of Starch Disappearance (min)

4 The independent variable is and should be plotted on the axis. The dependent variable is and should be plotted on the axis. Experiment C: The Effect of Temperature on Amylase Activity Formulate a question about temperature and reaction rate. Hypothesize about the time of starch disappearance at various temperatures. Time of starch disappearance in different temperatures for the enzyme amylase (do not exceed 4 min): Tube Temp. Time of Starch Disappearance (min) 1 80 o C 2 37 o C 3 22 o C 4 4 o C 76

5 The independent variable is and should be plotted on the axis. The dependent variable is and should be plotted on the axis. What do you think would happen to reaction rate in the tube incubated in ice if this tube, with enzyme and substrate already mixed, were placed in the 37 o C water bath? (explain your answer in terms of the effect of various temperatures on enzyme structure and the rate of enzyme activity) 77

6 REVIEWING YOUR KNOWLEDGE catalyst cofactor enzyme coenzyme substrate competitive inhibitor active site non-competitive inhibitor Compare and contrast competitive and noncompetitive inhibition. Why does adding additional substrate overcome competitive but not noncompetitive inhibition? 78