Energy and Enzymes Chapter 7 Lecture Outline

© 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.

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 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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© 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

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

© 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

© 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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© 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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© 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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© 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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© 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

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

© 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

© 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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© 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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© 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.

© 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

© 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

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

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

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

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

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

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

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

36 Discover Biology StudySpace

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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