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Energy and Enzymes

Chapter 7 Lecture Outline. Energy and Enzymes. Energy in Living Systems. Metabolism is the sum of all chemical reactions in the body. Metabolism transfers energy and follows the laws of thermodynamics. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e. 2. Laws of Thermodynamics.

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Energy and Enzymes

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  1. Chapter 7Lecture Outline Energy and Enzymes

  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. © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 2

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

  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 © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 4

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

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

  8. Using Energy from Food • Energy transfer in nonliving systems can be explosive: • Carbon in wood + O2  CO2 + H2O + energy • Energy transfer in cells must be controlled: • Carbon in food + O2  CO2 + H2O + energy © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 8

  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 © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 9

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

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  12. 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 © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 14

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

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  16. 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 © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 18

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

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

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

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  21. 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 © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 23

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

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

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

  27. 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

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

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

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

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

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

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

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

  35. 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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