1. Energy and Enzymes Chapter 7 Lecture Outline

2. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 2 Energy in Living Systems Metabolism is the sum of all chemical reactions in the body. Metabolism transfers energy and follows the laws of thermodynamics.

3. Laws of Thermodynamics 1 st Law: Energy cannot be either created or destroyed 2 nd Law: When reactions occur, they become more disordered © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 3

4. 4 The Carbon Cycle and Energy Living organisms all require energy to survive Sun is source of most energy on Earth Light energy is used by producers to synthesize sugars  Plants performing photosynthesis

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6. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 6 For non-photosynthesizing organisms (mostly consumers), energy is acquired from food molecules. Carbon dioxide and food molecules are involved in this energy transfer. The Carbon Cycle and Energy

7. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 7 The Carbon Cycle

8. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 8 Using Energy from Food Energy transfer in nonliving systems can be explosive:  Carbon in wood + O 2  CO 2 + H 2 O + energy Energy transfer in cells must be controlled:  Carbon in food + O 2  CO 2 + H 2 O + energy

9. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 9 Transfer of Electrons Capturing energy requires transfer of electrons Reactions that transfer electrons are called redox (oxidation/reduction) reactions  Oxidation—loss of electrons  Reduction—gain of electrons

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12. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 12 Metabolism All chemical reactions within living cells Anabolic  Biosynthetic: create complex molecules out of smaller compounds Catabolic  Break down complex molecules to release energy

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14. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 14 Chemical reactions and thermodynamics A + B  C + D  Reactants: A + B  Products: C + D Some chemical reactions need a “jump start” to proceed Activation energy:  Energy needed to jump ‑ start a reaction

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16. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 16 Enzymes Speed Up Reactions Enzymes are biological catalysts  Lower the energy of activation  Increase the speed of reaction

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18. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 18 The Structure of Enzymes Very specific for reactions Three ‑ dimensional shape determines function Active site is region where the substrate binds  Induced fit: active site molds around substrate

19. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 19 Enzymes as Molecular Matchmakers

20. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 20 Enzymes in Metabolism Metabolic pathways in the body usually involve several reactions. There may be several intermediates. Each intermediate has its own enzyme. BACD Enzyme 1Enzyme 2Enzyme 3

21. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 21 Enzyme Function Enzymes depend on random collisions. Multiple enzymes may be located close together. This maximizes molecular collisions.

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23. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 23 Metabolism and Life Span Slowing down metabolism increases life span Higher metabolism results in toxic by products (free radicals) Antioxidants help break down free radicals Some examples of antioxidants  Vitamin E  Vitamin C  Beta-carotene

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26. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 26 Concept Quiz Why are high fevers dangerous and sometimes life ‑ threatening? A. Molecules move faster at higher temperatures. B. Enzymes may change shape at high temperatures. C. Invading microbes survive better and reproduce faster at high temperatures.

27. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 27 Concept Quiz The loss of electrons is called A. Oxidation B. Reduction C. Redox

28. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 28 Concept Quiz Where a substrate binds to an enzyme is known as the A. Active site B. Activation energy C. Energy transfer site

29. Biology in the News Doctors Warned about Common Drugs for Pain; NSAIDs Tied to Risk of Heart Attack, Stroke  NSAIDs: Non ‑ steroid anti ‑ inflammatory drugs  Two major categories COX-1 inhibitors  May result in stomach problems COX-2 inhibitors  Long-term use associated with heart disease  Removed from the market © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 29

30. Terms Activation energy Active site Anabolic reaction Biosynthetic reaction Catabolic reaction Catalyst Coupled reaction Enzyme First law of thermodynamics Induced fit model Kinetic energy Metabolic pathway Metabolism Oxidation Potential energy © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 30

31. Terms Products Redox reaction Reactants Reduction Second law of thermodynamics Substrate © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 31

32. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 32 Process Animation 7.1a The Energy of Chemical Reactions  Macintosh Macintosh  Windows Windows

33. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 33 Process Animation 7.1b Heat and Chemical Reactions  Macintosh Macintosh  Windows Windows

34. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 34 Process Animation 7.1c Enzyme Catalysis  Macintosh Macintosh  Windows Windows

35. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 35 Process Animation 7.1d Enzymes and Activation Energy  Macintosh Macintosh  Windows Windows

36. 36 Discover Biology StudySpace http://www.wwnorton.com/college/biology/discoverbio4

37. 37 Additional Art from Chapter 7 All art files from the book are available in JPEG and PPT formats on the Instructor Resource Disc

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