Module 2 - 2a1 Intro to Bioenergetics Study of types of energy transformations that occur in living organisms Energy capacity to do work work to

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2a1: Intro to Bioenergetics Study of types of energy transformations that occur in living organisms Energy: capacity to do work; work: to change or move something Biological work: synthetic work (build up proteins, amino acids etc), mechanical work (kinesiology), concentration work (gradient), electrical work (membrane potential) Thermodynamics: study of changes in energy that accompany events in universe, predict direction of reaction, predict whether input of energy is required to cause an event to happen Favourable or unfavourable reactions, need to overcome energy barrier 2a2: Laws of Thermodynamics Energy cannot be created or destroyed o Can be converted from one form to another, ex. photosynthesis Events in the universe have direction o Events proceed from higher energy state to lower energy state o Such events are spontaneous, thermodynamically favourable and can occur without input of external energy o Amount of usable energy is reduced 2a3: Free Energy Delta G is a change during a process in the energy available to do work Negative free energy means energy transformation may proceed spontaneously o Thermodynamically favourable, exergonic process o Energy is available for use in another process Positive means transformation may not proceed o Thermodynamically unfavourable, endergonic o Energy must be added for process to proceed Standard free energy difference: ∆G°’
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o Difference in free energy when one mol of each reactant is converted to one mol of each product at 25C and 1atm Free energy changes in metabolic reactions o Cells can carry out many reactions with positive ∆G°’ o Ratio of reactant to product is maintained above that defined by equilibrium constant by other cellular reactions Couple endergonic and exergonic reactions o Coupling occurs when both reactions are catalyzed by the same enzyme 2a4: ATP and Coupled Reactions Hydrolysis of ATP drives endergonic reactions ATP + H2O ADP + phosphate, thermodynamically favourable ATP acts as common intermediate in biological-energy transfer 2a5: Oxidation-Reductions, Making of ATP Want to know if there are common processes by which we make ATP Loss of electrons from a substance is oxidation, gain is reduction Substance that is oxidized (donates electrons) is reducing agent Substance that is reduced (receives electrons) is oxidizing agent Oxidation state of carbon atom o Oxidized = oxygen added or hydrogen removed o Reduced = oxygen removed or hydrogen added Degree of reduction of a compound is a measure of its ability to perform chemical work within cell Carbohydrates rich in chemical energy because they contain strings of HCOH, ex. glucose
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This note was uploaded on 06/12/2011 for the course BIOL 130 taught by Professor Bols during the Fall '08 term at Waterloo.

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Module 2 - 2a1 Intro to Bioenergetics Study of types of energy transformations that occur in living organisms Energy capacity to do work work to

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