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Bio 121 Exam II Study Guide

Bio 121 Exam II Study Guide - Metabolism and Cellular...

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Metabolism and Cellular Respiration Review Chap 8 p141-154 Know catabolic vs anabolic pathways, potential energy, 1st and 2nd Laws of Thermo Catabolic pathways breakdown complex molecules (downhill) whereas anabolic pathways build complex molecules from simple molecules (uphill). Potential energy is energy that matter possesses because of its location or structure. The 1 st Law of Thermodynamics states energy and matter cannot be created or destroyed, but it can be transferred or transformed. The 2 nd Law of Thermodynamic states every energy transfer or transformation increases the disorder (entropy) of the universe. Entropy is the measurement of an increase or decrease in energy to do work. Understand Free energy and its relation to stability, work capacity, equilibrium (entropy and enthalpy). Free energy measures the portion of a system’s energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell. The more free energy (higher G) a system has makes it less stable and makes it obtain a greater work capacity. The less free energy (lower G) a system has makes it more stable and makes it obtain less work capacity. As a reaction proceeds toward equilibrium, the free energy of the mixture of reactants and products decreases. Free energy increases when a reaction is somehow pushed away from equilibrium, perhaps by removing some of the products. A system at equilibrium has a lower G value and any small change from the equilibrium position will have a positive ΔG. Understand exergonic (exothermic) vs. endergonic (endothermic) In an exergonic reaction, energy is released and the ΔG is negative. In an endergonic reaction, energy is required and the ΔG is positive. Understand metabolic disequilibrium, understand energy coupling, the importance of ATP, hydrolysis of ATP Metabolic disequilibrium is like a multistep open hydroelectric system. The products in a system become reactants in another reaction creating products that become reactants in another reaction, and so on. Energy coupling is the use of energy released from an exergonic reaction to drive an endergonic reaction. ATP is important because the energy it releases on hydrolyzing a phosphate group is greater than the energy most other molecules could deliver. It drives cellular work with its mechanical work (phosphorylating motor proteins), transport work (phosphorylating transport proteins), and chemical work (phosphorylating key reactants). It’s the cells energy currency. The hydrolysis of ATP breaks down its phosphate group yielding ADP and inorganic phosphate and in that process releases energy.
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Know Delta G for glucose, ATP, NADH rxns, know calorie vs. Calorie (kcal) The ΔG for glucose is -686 kcal/mol. The ΔG ATP is -7.3 kcal/mol.
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Bio 121 Exam II Study Guide - Metabolism and Cellular...

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