Chapter 8 An Introduction to Metabolism Metabolism Anabolism buildingsynthesis

Chapter 8 an introduction to metabolism metabolism

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Chapter 8: An Introduction to Metabolism * Metabolism= Anabolism (building/synthesis, ex: synthesis of protein from amino acids) + Catabolism (breaking down, ex: cellular respiration) 1. Kinetic vs Potential Energy. Examples A. Kinetic Energy : energy associated with motion. Heat (thermal energy)—KE associated with random movement of atoms/ molecules. Ex : Photons of light can be captured & their energy harnesses to power photosynthesis in green plants. B. Potential Energy : energy that matter possesses because of its location or structure. Chemical energy—PE available for release in chemical reaction. Ex: Water behind dam possesses energy because of its altitude above sea level. Molecules possess energy because of arrangement of their atoms. 2. Laws of Thermodynamics A. First Law of Thermodynamics (conservation of energy) Energy can be transferred and transformed, but it cannot be created or destroyed Energy of universe is constant quantity. - Plants do not produce energy, they transform light energy chemical energy. - During every transfer or transformation of energy, some energy is converted to heat, which is energy associated with random movement of atoms & molecules. - System can use heat to do work when there is tempt. Difference that results in heat flowing from warmer location to cooler one. - Chemical reactions in this brown bear will convert chemical (potential) energy in fish kinetic energy. B. Second Law of Thermodynamics Every energy transfer or transformation increases entropy of universe = For process to occur spontaneously, it must increase entropy of universe. - Energy transfer & transformation make universe more disordered (entropy) to loss of usable energy. - Organism takes in organized forms of matter and energy from its surroundings & replaces them with less ordered forms. - Entropy of particular system, such as organism, may decrease as long as total entropy of universe—system plus its surroundings—increases.
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- As it runs, disordered is increased around bear by release of heat and small molecules that are by-products of metabolism. 3. Relation between spontaneous/ non-spontaneous reactions & free energy & exergonic/endergonic A. Spontaneous Reactions : process occurs without input of energy; need not occur quickly, some are instantaneous (explosion), some are very slow (rusting of old car). B. Nonspontaneous reactions : process cannot occur on its own, will happen if energy is added to system. - Water flows downhill spontaneously but moves uphill only with input of energy, such as when machine pumps water against gravity. C. Free energy : measure of system’s instability, its tendency to change to more stable state. - During spontaneous change, free energy decreases (- G) & stability of system increases. D. Exergonic reaction —spontaneous; proceeds with net release of free energy (- G) E. Endergonic reaction —nonspontaneous; absorbs free energy from its surroundings (+ G) - Cells are not in equilibrium; they are open systems experiencing constant flow of materials.
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  • Spring '08
  • Satasivian
  • Adenosine triphosphate

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