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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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Chapter 7Lecture 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 • 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
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
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
The Carbon Cycle © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 7
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
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
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
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
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
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
Enzymes as Molecular Matchmakers © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 19
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
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
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
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
Concept Quiz The loss of electrons is called • Oxidation • Reduction • Redox © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 27
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
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 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
Terms Products Redox reaction Reactants Reduction Second law of thermodynamics Substrate © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 31
Process Animation 7.1aThe Energy of Chemical Reactions Macintosh Windows © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 32
Process Animation 7.1bHeat and Chemical Reactions Macintosh Windows © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 33
Process Animation 7.1cEnzyme Catalysis Macintosh Windows © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 34
Process Animation 7.1dEnzymes and Activation Energy Macintosh Windows © 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e 35
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Additional Art from Chapter 7 All art files from the book are available in JPEG and PPT formats on the Instructor Resource Disc