Energy And Metabolism PDF

08/10/23 Energy generation and metabolism: Learning objective: de ne and describe what is meant by energy, metabolism, anabolism and catabolism Learning objective: understand that life requires energy Learning objective: understand the relationship of life with the 2nd law of thermodynamics and the...

08/10/23 Energy generation and metabolism: Learning objective: de ne and describe what is meant by energy, metabolism, anabolism and catabolism Learning objective: understand that life requires energy Learning objective: understand the relationship of life with the 2nd law of thermodynamics and the tendency of systems to increase entropy Learning objective: de ne metabolism and understand what is meant by essential resources: proteins, lipids, polysaccharides, oxygen, water, inorganic ions, co-factors and waste products Energy and entropy: Entropy is disorder. The law of thermodynamics is that energy cannot be created nor destroyed, it can only be transferred from one form to another. Also that the entropy of an isolated system always increases. Living systems maintain low entropy by being open. Gibbed free energy: s G ( kJ/mol ) is a thermodynamic potential re ecting the max amount of available energy by a thermodynamically closed system at constant temp and pressure. IG Equilibrium reaction. O DG is neg DG is post co o Exergonic reaction, products have less energy than reactants Products have more energy than reactants Consider this reaction: substrate. Definition AG IG s cases forward or higher bored Positive substrate left so o DG Rs gas constant 09 movement net not backward implies forward or than at at Following Egm le proact so bald chattier's or so Egm forward pushed higher implies product love than substrate Do constant because DG C equilibrium DC standard natural I DG Negative to in is arise eqm keg hea in temperature three at substrate Rt energy substrate substrate product DG free energy product product Definition Ts Free RT In Egm at Product to or right less pushed principle back Biological energy and metabolic work: At the point of use, energy is almost invariantly supplied by ATP hydrolysis. ATP is made by processes of catabolism. ATP/ADP system is thereby an intermediary energy currency. Gibbs free energy of ATP hydrolysis determines energy available per ATP, and is an important regulatory signal. Variations in gibbs free for ATP can be an important metabolic signal, it,cannot be allowed to vary too much. DE DG Pi I s Hz POI these t RT HP CADD IN OF depends I are pi sources ATP is produced in two ways: 1. Substrate level phosphorylation: Uses ADP and a phosphate containing substrate ( e.g PEP or ADP ) PEP + ADP. Pyruvate + ATP. Or 2ADP. ( Pyruvate kinase ) catalysts ATP + AMP. ( adenylate kinase ) ATP Pi on the at pH balance each 2. Oxidative phosphorylation ( electron transport chain ): A series of reactions which high energy species release H+, and ATP generated. Metabolism: Anabolism + catabolism = metabolism Catabolism: things break down and produce energy Anabolism: things are built up which uses energy Amphibolic pathways can act in both anabolic and catabolic ways. Glycolysis: Generates 2NADH. They are turned back into NAD either by reducing Pyruvate to lactate or oxidised during ETC. 2ATP molecules are used up and 4 are produced, meaning there is a net gain of 2 ATP. Fates of Pyruvate: Anaerobic conditions: lactate Fed state: cellular respiration, via acetyl coA, the TCA cycle and oxidative phosphorylation Fasting state: used to make glucose ( gluconeogenesis ) via oxaloacetate Also transamination, to amino acids Oxidative phosphorylation: Electron transport chain= respiratory transport chain Located in the inner membrane of the mitochondria. It involves a series of components that oxidise reducing equivalents and use the energy to make ATP. Stoichiometry of energy production: Stoichiometry = the ratio bet ween quantities of reactants and products Examples: The carbon:oxygen Stoichiometry of glucose oxidation. Celtic Oo c O i e 6C I into go In CO2 the other 6 6 2 2 60 6410 602 half half 6 t lil Oxygen 2 6602 the Oxygen from glucose in CO2 6 6 1 I comes from On ATP:oxygen Stoichiometry of oxidative phosphorylation: P:O ratio Electrons from NADH pass down the ETC to eventually reduce oxygen NADH Ht 4202 NAD't H2O During this process, the other H+ are pumped into the intermembrane space Some H+ leak back in, producing only heat Some H+ re-enter via the ATP Synthase and drive ATP synthesis Uncouplers increase the leak, reducing ATP yield and increasing heat production All these factors in uence P:O