Chapter 8 - Chapter 8: An Introduction to Metabolism...

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Chapter 8: An Introduction to Metabolism Overview: The Energy of Life The living cell is a miniature chemical factory where thousands of reactions occur The cell extracts energy and applies energy to perform work Some organisms even convert energy to light, as in bioluminescence Concept 8.1: An organism’s metabolism transforms matter and energy, subject to the laws of thermodynamics Metabolism is the totality of an organism’s chemical reactions Metabolism is an emergent property of life that arises from interactions between molecules within the cell Organization of the Chemistry of Life into Metabolic Pathways A metabolic pathway begins with a specific molecule and ends with a product Each step is catalyzed by a specific enzyme Catabolic pathways release energy by breaking down complex molecules into simpler compounds Cellular respiration, the breakdown of glucose in the presence of oxygen, is an example of a pathway of catabolism Anabolic pathways consume energy to build complex molecules from simpler ones The synthesis of protein from amino acids is an example of anabolism Bioenergetics is the study of how organisms manage their energy resources Forms of Energy Energy is the capacity to cause change Energy exists in various forms, some of which can perform work Kinetic energy is energy associated with motion Heat (thermal energy) is kinetic energy associated with random movement of atoms or molecules Potential energy is energy that matter possesses because of its location or structure Chemical energy is potential energy available for release in a chemical reaction Energy can be converted from one form to another Some energy is always lost as heat when conversion occurs The Laws of Energy Transformation Thermodynamics is the study of energy transformations A closed system, such as that approximated by liquid in a thermos, is isolated from its surroundings In an open system, energy and matter can be transferred between the system and its surroundings Organisms are open systems The First Law of Thermodynamics According to the first law of thermodynamics , the energy of the universe is constant: Energy can be transferred and transformed, but it cannot be created or destroyed The first law is also called the principle of conservation of energy The Second Law of Thermodynamics During every energy transfer or transformation, some energy is unusable, and is often lost as heat According to the second law of thermodynamics :
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Every energy transfer or transformation increases the entropy (disorder) of the universe Living cells unavoidably convert organized forms of energy to heat Spontaneous processes occur without energy input; they can happen quickly or slowly
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Chapter 8 - Chapter 8: An Introduction to Metabolism...

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