October 10 (students).pdf - Biol 1020 A06 Oct 10 Major...

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Biol 1020 A06 Oct 10
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Major themes of this lecture Feedback inhibition Energy profiles of reactions Role of NADH as an electron carrier Overview of cellular respiration Common reactions in cellular respiration
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Regulation of metabolic pathways: feedback inhibition Allows a pathway to be shut down when its products are not needed An intermediate or final product of the pathway typically inhibits an enzyme in the pathway Can be at an allosteric or active site Threonine Enzyme 1 threonine deaminase End product- isoleuciene
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Cell is using product (isoleucine): Product of the pathway does not build up-initial substrate can bind to active site Cell is not using product(isoleucine) : Product of the pathway builds up, can inhibit an enzyme in the pathway
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matter and energy are conserved there is always an increase in disorder; entropy always increases Metabolism is governed by thermodynamics Cells create ordered structures from less ordered materials Creates disorder elsewhere ( eg through molecules and heat)
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Free energy changes and metabolic reactions Free energy- G- energy in a system that can be used to do work High free energy- high ability to do work Low free energy low ability to do work
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Free energy Need an input of energy to move a reaction out of equilibrium
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Δ G = G final G starting Energy profiles - Endergonic reaction Requires energy input
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Energy profiles- exergonic reaction Δ G = G final G starting ATP → ADP + Pi ∆G = - 7.3 kcal/mol Energy is released by the reaction Can be use to power and endergonic reaction
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Activation energy of chemical reactions Reactant Products Energy of activation : energy that must be absorbed for the reaction to reach the transition state
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Enzymes speed up reactions by lowering E A By allowing molecules to absorb energy to reach transition state Microenvironment of active site Proper orientation of substrates Stressing bonds that must be broken Direct participation
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How do endergonic reactions occur in cells?
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