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This 5 page Class Notes was uploaded by Kezia Notetaker on Tuesday September 27, 2016. The Class Notes belongs to bio1134 at Mississippi State University taught by Martha Barton in Fall 2016. Since its upload, it has received 8 views. For similar materials see General Biology I in Biology at Mississippi State University.
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Date Created: 09/27/16
CHAPTER 6: ENERGY, ENZYME, AND METABOLISM Energy and Chemical Reaction Energy is the ability to do work. Kinds/ forms of energy: o Kinetic energy: associated with movement. o Potential energy: due to structure or location of the thing. o Chemical energy: the energy which is stored in chemical bonds in form of potential energy. (2 factors that govern the fate of chemical energy are direction and rate) Laws of Thermodynamics o First Law (Law of conservation of energy) Energy cannot be created or destroyed, but can be transformed from one type to another. o Second Law Transfers of energy from one form to another increases the entropy (degree of disorder) of a system. Note this: if entropy increases, there will be less energy for an organism to use to do work. Chemical reaction happens when 1 or more substances forms a different substance (reactant product) or when an existing chemical bonds are broken and new chemical bonds are formed. Ex: Total energy formula: H= G + TS H= enthalpy/ total energy G= free energy/ usable energy/Gibbs energy S= entropy/ unusable energy T= temperature in Kelvin (K) How to determine if a reaction is spontaneous? ΔG = Δ H – T Δ S o Exergonic: spontaneous (ΔG = -) release energy o Endergonic: not spontaneous (ΔG = +) requires energy Redox reaction o Reduction: addition of electron o Oxidation: removal of electron Ae- + B → A + Be- A = oxidation B= reduction Enzymes and Ribozymes Enzyme: protein that performs as catalyst (an agent that speeds up the rate of chemical reaction but isn’t being consumed in the reaction) in living cells. Ribozyme: RNA molecules with catalytic properties. Enzyme terminology: o Active site: the place where substrates will attach/ reaction occurs. o Substrate: reactants that binds to the active site of an enzyme. o Enzyme-substrate complex: an intermediate formed when an enzyme binds with its substrate. o Product: molecules that which is formed after the reaction. Activation energy o Activation energy: input of energy that is needed to start a reaction. o Ways to overcome activation energy: Large amount of heat Use the enzyme (catalyst) to lower the activation energy Factors that affects enzyme catalyzed reaction o Increasing substrate concentration increases the reaction rate. o Increasing enzyme concentration increases the reaction rate. o PH; affects the ionic bonds that are needed for protein folding. o Temperature (high: denatures the enzyme; low: slowdown the reaction rate) Enzyme inhibitors o Competitive inhibitor: the inhibitor that compete with the substrate to bind to an enzyme’s active site o Noncompetitive inhibitor: the inhibitor that binds to another part of an enzyme (allosteric site) to inhibits the reaction. Overview of Metabolism Metabolism refers to all chemical reaction that happens within cells where each steps are coordinate by a specific enzyme. Catabolism o Break-down the molecules; used to recycle the building blocks. o It’s an exergonic reaction (release energy) Anabolism o Build molecules and macro molecules o It’s an endergonic reaction (requires energy) o Forms intermediates (NADH and ATP) to drive reactions. o Products have less o There’s a net release of energy than the energy. reactant. o There’s a net input of o Products has more energy. energy than the reactant. o 2 ways to make ATP o Substrate level phosphorylation: enzyme directly transfer phosphate from one molecule to another. o Chemiosmosis: energy stored in chemical gradient is used to make ATP from ADP and Phosphate. o The use of NADH o Releases a lot of energy when oxidized, used to make ATP. o Can donate electrons during synthesis reactions to energize them. o Regulation of metabolic pathways o Gene regulation: turns gene on and off o Cellular regulation: cell-signals pathways like hormones o Biochemical regulation: feedback inhibition (product of pathway inhibits early steps to prevent from over accumulation of product). o o o o
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