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Bio Exam 3 Notes

Bio Exam 3 Notes - Chapter 8 An Introduction to...

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Chapter 8: An Introduction to Metabolism (142-159) The Energy of Life 1) 8.1 An organism’s metabolism transforms matter and energy, subject to the laws of thermodynamics i) Metabolism : the totality of an organism’s chemical reactions. b) Organization of the Chemistry of Life into Metabolic Pathways i) Metabolic pathways : begins with a specific molecule, which is then altered in a series of defined steps, resulting in a certain product. Each step of the pathway is catalyzed by a specific enzyme. ii) Catabolic pathways : metabolic pathways that release energy by breaking down complex molecules to simpler compounds; breakdown pathways (cellular respiration) iii) Anabolic pathways : consume energy to build complicated molecules from simpler ones; biosynthetic pathways (synthesis of a protein from amino acids) iv) Bioenergetics : the study of how energy flows through living organisms c)Forms of Energy i) Energy : capacity to cause change; ability to rearrange a collection of matter ii) Kinetic energy : energy associated with relative motion of objects iii) Heat/Thermal energy : kinetic energy associated with the random movement of atoms or molecules. iv) Potential energy : energy that matter possesses because of its location or structure. v) Chemical energy : the potential energy available for release in a chemical reaction. d) The Laws of Energy Transformation i) Thermodynamics : the study of the energy transformations that occur in a collection of matter (1) The First Law of Thermodynamics : Energy can be transferred and transformed, but it cannot be created or destroyed. (2) The Second Law of Thermodynamics : Every energy transfer or transformation increases the entropy of the universe; for a process to occur spontaneously, it must increase the entropy of the universe. (a) Entropy : Measure of disorder, or randomness (b) Spontaneous: process that can occur without an input of energy (3) Biological Order and Disorder 2) 8.2 The free-energy change of a reaction tells us whether or not the reaction occurs spontaneously a)Free-Energy Change, G i) Universe = systems + surroundings ii) Free energy : portion of a system’s energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell. iii) G = H (H: enthalpy: equivalent to total energy) - T S (S: system’s entropy; T in Kelvin) [negative G are spontaneous] b) Free Energy, Stability, and Equilibrium i) G = G final state – G initial state
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ii) Free energy: a measure of a system’s instability—its tendency to change to a more stable state iii) Unstable systems (higher G) tend to change in such a way that they become more stable (lower G) iv) Equilibrium: state of maximum stability, G is at it’s lowest possible value in that system; systems never spontaneously move away from equilibrium v) A process is spontaneous and can perform work only when it is moving toward equilibrium. c)Free Energy and Metabolism
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Bio Exam 3 Notes - Chapter 8 An Introduction to...

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