Ch. 6 & 7: Enzymes, Metabolism & Cellular Respiration
Ch. 6 & 7: Enzymes, Metabolism & Cellular Respiration 110
University of Louisiana at Lafayette
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This 7 page Study Guide was uploaded by Antonio Cannet on Wednesday February 17, 2016. The Study Guide belongs to 110 at University of Louisiana at Lafayette taught by Dr. Kreyeski in Winter 2016. Since its upload, it has received 49 views. For similar materials see Fund of Biology I in Biology at University of Louisiana at Lafayette.
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Date Created: 02/17/16
Ch. 6 The first law of thermodynamics >Law of conservation of energy >Energy cannot be created nor destroyed Ex: Chemical energy is transformed into heat The second law of thermodynamic > Transfer or transformation of energy from one form to another increases entropy or degree of disorder of a system >Disorder (entropy) increases > Biological processes are not 100% efficient Ex: A chemical reaction may release unusable heat Energy ability to promote change; (the capacity to do work, including changing one molecule into another molecule) Kinetic energy Associated with movement Ex: the movement of a baseball bat from one location to another Potential energy The energy that an object has due to structure or location Entropy A measure of the disorder that cannot be harnessed to do work Enthalpy The heat content of a system at constant pressure Free energy The amount of available energy that can be used to promote or do work Exergonic >Negative free energy change > Spontaneous Endergonic > Positive free energy change > Requires addition of free energy > Not spontaneous Delta G Change in free energy ATPA molecule that is a common energy source for all cells. Activation energy > Initial input of energy to start reaction > Allows molecules to get close enough to cause bond rearrangement > Can now achieve transition state where bonds are stretched Active site Location where reaction takes place Substrate Reactants that bind to active site Allosteric site A site on an enzyme other than the active site, to which a specific substance binds, thereby changing the shape and activity of the enzyme. What is an enzyme and what does it do? Enzymes are often proteins (but they can be ribozymes) and are the most common catalyst Catalyst agent that speeds up the rate of a chemical reaction without being consumed during the reaction Explain competitive and noncompetitive enzymes Biochemical regulation >Competitive inhibitors: compete for access to an enzyme's active site > Noncompetitive inhibitors: bind outside the active site [Slide 36] Describe a metabolic pathway (in general). How are enzymes involved? Chemical reactions occur in metabolic pathways Each step is coordinated by a specific enzyme > Result in breakdown and are exergonic Anabolic pathways > Promote synthesis and are endergonic > Must be coupled to exergonic reaction Describe a redox or oxidation reduction reaction. Oxidation > Removal of elections Reduction > Addition of electrons Redox > Electron removed from one molecule is added to another Ch. 7 Substrate Level phosphorylation > Enzyme directly transfers phosphate from one molecule to another molecule > Oxygen not needed Chemiosmosis > Energy stored in an electrochemical gradient is used to make ATP from ADP and Pi > Oxygen required Cellular respiration Process by which living cells obtain energy from organic molecules Primary aim to make ATP and NADH Aerbic respiration uses oxygen > O2 consumed and CO2 released Glucose metabolism 4 metabolic pathways 1. Glycolysis 2. Breakdown of pyruvate to an acetyl group 3. Citric acid cycle 4. Oxidative phosphorylation *Electron transport chain and chemiosmosis Stage 1: Glycolysis Glycolysis can occur with or without oxygen and it occurs in the cytoplasm Steps in glycolysis nearly identical in all living species 10 steps in 3 phases 1. Energy investment 2. Cleavage 3. Energy liberation 3 phases of glycolysis Stage 1. Energy investment Steps 13 2 ATP hydrolyzed to create fructoses 2. Cleavage Steps 45 6 carbon molecule broken into two 3 carbon molecules of glyceraldehyde3phosphate 3. Energy liberation Steps 610 Two glyceraldehyde3phosphate molecules broken down into two pyruvate moles producing 2 NADH and 4 ATP Stage 2: Breakdown of pyruvate to an acetyl group In eukaryotes, pyruvate in transported to the mitochondrial matrix Broken down by pyruvate dehydrogenase Molecule of CO2 removed from each pyruvate Remaining acetyl group attached to CoA to make acetyl CoA Stage 3: Citric acid cycle Metabolic cycle >Particular molecules enter while other leave, involving a series of organic molecules regenerated with each cycle Acetyl is removed from Acetyl CoA and attached to oxaloacetate to form citrate or citric acid Series of steps releases 2CO2, 1ATP, 3NADH, and 1 FADH2 Oxaloacetate is regenerated to start the cycle again Stage 4: Oxidative phosphorylation High energy electrons removed from NADH and FADH2 to make ATP Typically requires oxygen Oxidative process involves electron transport chain Phosphorylation occurs by ATP synthase Electron transport chain Group of protein complexes and small organic molecules embedded in the inner mitochondrial membrane Can accept and donate electrons in a linear manner in a series of redox reactions Movement of electrons generates H+ electrochemical gradient/ proton motive force >Excess of positive charge outside of matrix Free energy change Movement from NADH to O2 is a very negative free energy change >Spontaneous in forward direction Highly exergonic Some energy used to pump H+ across inner mitochondrial membrane and create H+ electrochemical gradient ATP synthase Enzyme harnesses free energy as H+ flow through membrane embedded region Energy conversion H+ electrochemical gradient or proton motive force converted to chemical bond energy in ATP Racker and Stoeckenius confirmed ATP uses an H+ electrochemical gradient Rotary machine that makes ATP as it spins Anaerobic metabolism For environments that lack oxygen or during oxygen deficits 2 strategies >Use substance other than O2 as final electron acceptor in electron transport chain >If confined to using O2, carry out glycolysis only >Pyruvate converted to lactate or lactic acid in muscles or ethanol is yeast >Fermentation produces far less ATP Secondary Metabolism Primary metabolism essential for cell structure and function Secondary metabolism synthesis of secondary metabolites that are not necessary for cell structure and growth Secondary metabolites unique to a species or group Roles in defense, attraction, protection, competition 4 categories Phenolics >Antioxidants with intense flavors and smells Alkaloids Bittertasting molecules for defense Terpenoids >Intense smells and colors Polyketides >Chemical weapons
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