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Topic Four: Enzymes Student Notes

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IB Biology 2015 Curriculum

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Topic Four: Enzymes Student Notes

  1. 1. SevenQuest TopicFour:Enzymes CommackHighSchoolHLBiology
  2. 2. 1 http://bioknowledgy.weebly.com/ (Chris Paine) Understandings, Applications and Skills (This is what you maybe assessed on) Statement Guidance 2.5 U.1 Enzymes have an active site to which specific substrates bind. 2.5 U.2 Enzyme catalysis involves molecular motion and the collision of substrates with the active site. 2.5 U.3 Temperature, pH and substrate concentration affect the rate of activity of enzymes. Students should be able to sketch graphs to show the expected effects of temperature, pH and substrate concentration on the activity of enzymes. They should be able to explain the patterns or trends apparent in these graphs. 2.5 U.4 Enzymes can be denatured. 2.5 U.5 Immobilized enzymes are widely used in industry. 2.5 A.1 Methods of production of lactose-free milk and its advantages. Lactase can be immobilized in alginate beads and experiments can then be carried out in which the lactose in milk is hydrolysed. 2.5 S.1 Design of experiments to test the effect of temperature, pH and substrate concentration on the activity of enzymes. 2.5 S.2 Experimental investigation of a factor affecting enzyme activity. (Practical 3) Understandings, Applications and Skills (This is what you maybe assessed on) Statement Guidance 8.1 U.1 Metabolic pathways consist of chains and cycles of enzyme-catalysed reactions. 8.1 U.2 Enzymes lower the activation energy of the chemical reactions that they catalyse. 8.1 U.3 Enzyme inhibitors can be competitive or non-competitive. Enzyme inhibition should be studied using one specific example for competitive and non-competitive inhibition. 8.1 U.4 Metabolic pathways can be controlled by end-product inhibition. 8.1 A.1 End-product inhibition of the pathway that converts threonine to isoleucine.
  3. 3. 2 http://bioknowledgy.weebly.com/ (Chris Paine) 8.1 A.2 Use of databases to identify potential new anti-malarial drugs. 8.1 S.1 Calculating and plotting rates of reaction from raw experimental results. 8.1 S.2 Distinguishing different types of inhibition from graphs at specified substrate concentration. 2.5 U.1 Enzymes have an active site to which specific substrates bind. (Use the hyperlink below) http://highered.mheducation.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html 1. Define the following terms: a. Enzyme b. Active site c. Substrate d. Product 8.1 U.2 Enzymes lower the activation energyof the chemical reactions that they catalyse. 2. What suffix is commonly applied to enzymes? (Slide 8) 3. Define activation energy? (Slide 9-10) 4. What effect do enzymes have on the activation energy of a reaction? (Slide 8-10) 5. Complete the sketch graph to show how enzymes reduce the activation energy required for a reaction to occur. (Slide 10)
  4. 4. 3 http://bioknowledgy.weebly.com/ (Chris Paine) 6. Explain enzyme-substrate specificity, using a diagram and referring to the lock-and-key model.(Slide 11) 7. State the function of polar region of amino acids on the active site of the enzyme. (Slide 11-12) 8. Describe the induced-fit model of enzyme activity, with reference to the lock and key theory, conformational change and activation energy. (Slide 12) 2.5 U.2 Enzyme catalysis involves molecular motion and the collision of substrates with the active site (Slide 13) Play with the animation, by changing concentrations. 9. State what is meant by the term collision in enzyme catalysis. (Slide 13) 10. Explain why not all collisions between enzymes and substrates result in catalysis. (Slide 13)
  5. 5. 4 http://bioknowledgy.weebly.com/ (Chris Paine) 11. Explain why the presence of water is critical for most enzyme reactions.(Slide 14) 12. Enzymes can be immobilized (e.g. embedded in cell membranes). Enzymes can also be free to move, but they tend to move more slowly than substrates, explain why. (Slide 14) 13. Describe three examples of enzymes giving the substrates and products.(Slide 15) Enzyme Substrate Product 2.5 U.3 Temperature, pH and substrate concentration affect the rate of activity of enzymes. 14. List the factors that affect the rate at which enzymes work (Slide 16) * * * * * * * 15. Explain the effects of temperature, pH and substrate concentration on the rate of an enzyme-controlled reaction. Temperature (Slide 17)
  6. 6. 5 http://bioknowledgy.weebly.com/ (Chris Paine) pH (Slide 20) Substrate concentration (Slide 23) 2.5 U.4 Enzymes can be denatured.(slide19) 16. With the use of annotated diagrams explain how the denaturing of an enzyme affects its ability to catalyse reactions.
  7. 7. 6 http://bioknowledgy.weebly.com/ (Chris Paine) 8.1 U.1 Metabolic pathways consist of chains and cycles of enzyme-catalysed reactions. 17. Define metabolism.(Slide 24) 18. Describe what a metabolic pathway is and state how each step in the pathway is controlled. (Slide 24- 25) 19. Give an example of a linear metabolic pathway. (Slide 24) 20. Give an example of a metabolic pathway that is a cycle. (Slide 26) 8.1 U.3 Enzyme inhibitors can be competitive or non-competitive. 21. Define an inhibitor. (Slide 27) 22. Using diagrams, explain the difference between competitive and non-competitive methods of inhibition.(Slide 28 and Slide 30) 23. Outline one example of a competitive inhibitor. (Slide 29) 24. Outline one example of one non-competitive inhibitor. (Slide 31)
  8. 8. 7 http://bioknowledgy.weebly.com/ (Chris Paine) 8.1 S.2 Distinguishing different types of inhibition from graphs at specified substrate concentration. 25. Sketch a graph to compare the effects of competitive and non-competitive inhibitors on the rate of enzyme activity at different substrate concentrations. Add annotations to explain the different effects the different types of inhibitor have upon the rate of enzyme activity. (Slide 32-33) 26. Three experiments were carried out to measure the effect of inhibitor concentration upon an enzymes rate of reaction. The results for each experiment are shown in the graph below. From IB Biology past papers [Source: R Taber, Biochemical Education, (1998) 26, pages 239-242] a. Outline the effect of increasing the substrate concentration on the control reaction (no inhibition). b. State the initial rate of reaction at an ethanol concentration of 50 mmol dm–3 in the presence of the inhibitor at the following concentrations. 1 mmol dm–3: 3 mmol dm–3: c. State the effect of increasing the concentration of inhibitor on the initial rate of reaction 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 10 20 30 40 50 60 70 80 90 100 Ethanol concentration / mmol dm–3 Initial rate of reaction / arbitrary units –3 –3 no inhibition 1 mmol dm inhibitor 3 mmol dm inhibitor
  9. 9. 8 http://bioknowledgy.weebly.com/ (Chris Paine) 8.1 U.4 Metabolic pathways can be controlled by end-product inhibition. 27. Explain the role of end-product inhibition as a method of controlling metabolic pathways. Include the role of allosteric sites.(Slide 34) 8.1.A2 Use of databases to identify potential new anti-malarial drugs. 28. What causes the disease malaria? (Slide 34) 29. Bioinformatics has facilitated research into metabolic pathways is referred to as chemogenomics. Outline the process of chemogenomics. (Slide 35-36) 30. Describe what is meant by the term Bioinformatics.(Slide 37)
  10. 10. 9 http://bioknowledgy.weebly.com/ (Chris Paine) 8.1.S1 Calculating and plotting rates of reaction from raw experimental results. Virtual Lab: Enzyme Controlled Reactions Click through this link to the virtual lab: http://www.mhhe.com/biosci/genbio/virtual_labs_2K8/labs/BL_02/index.html Follow the instructions carefully below and during the lab. QUESTIONS How will substrate concentration affect the ability of an enzyme to catalyze a reaction? How will pH affect the ability of an enzyme to catalyze a reaction? BACKGROUND 1. What enzyme are you using in this lab?________________________ 2. What is the substrate?____________________________ 3. Describe the reaction this enzyme catalyzes: 4. Which of the following does NOT apply to an enzyme: a. Catalyst b. Inorganic c. Protein d. All of the above PROCEDURE RESULTS: Table 1: Record your data on the number of product molecules formed per minute obtained from the virtual lab. ***Note: there is also a “Graph” tab at the top of the page with this table. You’ll need to look at that later. # Product Molecules/minute at: Amount of Substrate (Lactose) pH 3 pH 5 pH 7 pH 9 pH 11 0.5 g 1.0 g 2.0 g 4.0 g 8.0 g
  11. 11. 10 http://bioknowledgy.weebly.com/ (Chris Paine) Graph your results in the space below. Place pH on the x-axis and number of product molecules produced on the y-axis. Don't forget a title and axes labels. 1. What substrate amount was required to achieve the maximum reaction rate?__________________ 2. At what pH level did the maximum reaction rate occur?_______________________ 3. Why was there no increase in the reaction rate with 8.0 g. of substrate as compared to 4.0 g. of substrate? What would you need to add to see an increase in the reaction rate with 8.0 g. of substrate? 4. In the graph you created in the lab simulation with your data: a. What is represented by the green line? b. What is the optimal pH for lactase enzyme activity? 5. Consider only the experiment you conducted with a constant amount of lactose. a. What is the independent variable?_________________________________ b. What is the dependent variable?__________________________________
  12. 12. 11 http://bioknowledgy.weebly.com/ (Chris Paine) 2.5 U.5 Immobilized enzymes are widely used in industry. 31. Enzymes used in industry are commonly immobilized. a. Describe the advantages of immobilizing enzymes.(Slide 39) b. List three ways in which enzymes can be immobilized. (Slide 39)    32. List eight common uses of enzymes in industry.(Slide 40) 2.5 A.1 Methods of production of lactose-free milk and its advantages. 33. Although all children produce lactase some adults are lactose intolerant, they lose the ability to produce lactase in adulthood. Explain why. (Slide 48) a. State the three other commercial reasons that lactose free milk is produced. (Slide 51)    b. Outline the process by which lactose-free milk is produced by immobilized enzymes. (Slide 51) Citations: Allott, Andrew. Biology: Course Companion. S.l.: Oxford UP, 2014. Print. Taylor, Stephen. "Essential Biology 03.6 07.6 C2 Enzymes.docx." Web. 1 Oct. 2014. <http://www.slideshare.net/gurustip/essential-biology-36-76-c2-enzymes>.

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