Lect-4-SV

Lect-4-SV - 10-09-07: Lecture 4 Bioenergetics: Cell as a...

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10-09-07: Lecture 4 Bioenergetics: Metabolism: All the chemical processes of the cell. Catabolic Pathways: Anabolic pathways: Cell as a Chemical Factory build amino acids (a.a.) A.A. Protein Nucleotides (NT) DNA or RNA Photosynthesis:
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Bioenergetics: All metabolic pathways are subject to the 1 st and 2 nd laws of thermodynamics 1 st : Energy can be transferred or transformed, but it can not be created or destroyed 2 nd : Every process in the universe increases Disorder (Entropy) Na + Diffusion 10-09-07: Lecture 4 Na + Diffusion
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Bioenergetics: Chemical reactions in the cell •All controlled , stepwise fashion •Compartmentalized •Requires enzymes (proteins) •Serve as a catalyst – can be re-used •Increase entropy •Increase rate of the reaction (rxn) Chemical RXNs Spontaneous: Non-Spontaneous: G = Gibbs free energy G = G products G reactants Free energy of a reaction from the final state and the initial state 10-09-07: Lecture 4
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G = Gibbs free energy – amount of energy that is capable of doing work during a reaction at constant pressure and constant temperature. •When a system changes to possess less energy (free energy is lost) than the free energy change ( G) is negative and the reaction is exergonic (spontaneous) Enthalpy : the heat content of a system (H). When a chemical reaction releases heat it is exothermic and has a negative ( H). Entropy : Randomness or disorder of a system . When the products of a reaction are less complexed and more disordered than the reactants, the reaction proceeds with a gain in entropy ( S). G = H – T S 10-09-07: Lecture 4
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Free energy of a reaction from the final state and the initial state G = Gibbs free energy G = G products G reactants Bioenergetics: G H H < 0 H > 0 T - temp S Entropy S < 0 S > 0 : free energy (amount of energy that can do work) : Enthalphy (heat) : heat released – break a bond : heat infused (absorbed) – create a bond : constant : create order : create disorder 10-09-07: Lecture 4
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Bioenergetics: Enthalpy and Entropy G = H – T S G < 0 Will be spontaneous because: H < 0 Released heat
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Lect-4-SV - 10-09-07: Lecture 4 Bioenergetics: Cell as a...

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