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Principles of METABOLISM Basic concepts
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Metabolism purposes 1-Obtain energy 2-convert nutrient molecules into the cell’s own characteristic molecules 3-polymerize monomers precursors into macromolecules 4-synthesize and degrade biomolecules required for specialized cellular functions
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Metabolism, the sum of all the chemical transformations taking place in a cell or organism, occurs through a series of enzyme-catalyzed reactions that constitute metabolic pathways.
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Chemical reactions in metabolism Most of the reactions in living cells fall into one of five general categories: 1- oxidation-reductions; 2- reactions that make or break carbon–carbon bonds; 3- internal rearrangements, Isomerizations, 4- group transfers; and (5) free radical reactions.
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1. Oxidation-reduction reactions
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2. Reactions that make or break carbon–carbon bonds
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3. Internal rearrangements, isomerizations, and eliminations
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4. Group transfer reactions
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5. Free radical reactions
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Enzymes
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Enzyme as biocatalist
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Specify
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Active site
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kinetics
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inhibition
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Bioenergetics:The Role of ATP Biologic Systems Conform to the General Laws of Thermodynamics 1-The total energy of a system, including its Surroundings remains constant 2-The total entropy of a system must increase if ∆G<0 ΔG = ΔH− TΔS ΔG = ΔE − TΔS if ∆G<0 exergonic if ∆G>0 endergonic equilibrium if ∆G=0 ΔG0′ = −RT ln K ′eq When the reactants are present in concentrations of 1.0 mol/L, ΔG0 is the standard free energy change
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Coupling reactions
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ATP The nucleotide coenzyme adenosine triphosphate (ATP) is the most important form of chemical energy in all cells. Cleavage of ATP is strongly exergonic.
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HIGH-ENERGY PHOSPHATES PLAY A CENTRAL ROLE IN ENERGY CAPTURE AND TRANSFER
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Energy charge in cells
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Main sources of ATP (1) Oxidative phosphorylation: The greatest quantitative (2) Glycolysis (3) The citric acid cycle
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Oxidative phosphorylation
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Chemiosmatic hypothesis(mitchell)
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Redox potential
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The Respiratory Chain Consists of Four Complexes: Three Proton Pumps and a Physical Link to the Citric Acid Cycle Electrons are transferred from NADH to O2 through a chain of three large protein complexes called NADH-Q oxidoreductase, Succinate dehydrogenase, Q-cytochrome c oxido-reductase, and cytochrome c oxidase
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Electrons Flow from Ubiquinol to Cytochrome c Through Q-Cytochrome
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