Weekly Notes Chapter 8 and beginning of Chapter 9
Weekly Notes Chapter 8 and beginning of Chapter 9 BSC 2010
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This 11 page Class Notes was uploaded by Meghan Cooper Mendes de Oliveira on Saturday October 3, 2015. The Class Notes belongs to BSC 2010 at Florida State University taught by Dr. Steven Marks in Fall 2015. Since its upload, it has received 103 views. For similar materials see Biological Science in Biological Sciences at Florida State University.
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Date Created: 10/03/15
BSC 2010 Thursday September 24 2015 Chapter 8 Metabolism 39 Overview the Energy of Life 39 living cell is a miniature chemical factory with thousands of reactions 39 cell extracts energy ATP and apple energy to perform work 39 Organisms even convert energy to light 39 four key concepts 1 An organism s metabolism transforms matter and energy 2 Spontaneity of a reaction depends of the change in freeenergy 3 ATP powers cellular work by coupling exergonic reactions and endergonic reactions 4 Enzymes catalyze reactions by lowering required activation energy 39 What is Metabolism 39 the totality of an organism s chemical reactions 39 a metabolic pathway begins with a specific molecule ends with a product 39 Catabolic pathways release energy through the breakdown of large complex molecules into smaller simpler compounds 39 cellular respiration is an example 39 Anabolic pathways consume energy to build complex molecules from simpler ones 39 synthesis of proteins 39 Forms of Energy Thursday September 24 2015 39 Energy ability to cause change 39 Kinetic energy motion energy 39 a windmill converts moving wind into electrical energy 39 Thermal energy heat kinetic energy random movements of molecules 39 Potential energy energy locked in a molecule stored energy 39 Chemical energy potential energy that can be released through chemical reactions 39 Laws of Energy 39 Thermodynamics study of energy transformation 39 rst law of thermodynamics 39 energy cannot be created or destroyed 39 energy can be transferred or transformed 39 energy in the universe is constant 39 Second law of thermodynamics 39 every energy transfer or transformation must increase the entropy of the universe 39 Entropy disorder 39 Order and disorder within the cell 39 Cells create order from disorder 39 replace matter and energy that is ordered with a disordered form 39 Energy 2 Light Thursday September 24 2015 39 exists in the form of heat 39 Spontaneous and NonSpontaneous Reactions Exergonic Spontaneous reactions release energy Endergonic NonSpontaneous Reactions absorb energy A Change in Free Energy AG Free energy is the energy an organism has available to perform work in a uniform temperature and pressure environment 39 G Gibbs free energy of a system 39 Free Energy Stability and Equilibrium Free energy is the instability of a system will it change to a more stable state how likely is it to change Spontaneous changes will decrease free energy and the system will become more stable At Equilibrium the system is extremely stable the system will not change The process will only occur as a system is working toward equilibrium 39 Free Energy and Metabolism How does Free energy relate to the Metabolisms 39 Exergonic reactions release free energy from a system and bring the system closer to stability and equilibrium 39 Endergonic reactions absorb free energy into a system and makes the system more unstable 39 Equilibrium and the Metabolism Thursday September 24 2015 39 In a closed system reactions will eventually bring the system to equilibrium and will no longer do work 39 Cells are never in equilibrium they are open systems 39 metabolism is never in equilibrium 39 Catabolic pathways release free energy 39 ATP powers the cell by using both exergonic and endergonic reactions 39 Three main types of work 39 Chemical 39 Transport 39 Mechanical 39 Energy coupling how cells manage energy resources 39 use exergonic reactions to run endergonic reactions 39 Most is mediated by ATP 39 Regenrating ATP 39 It is a renewable resource 39 regenerated by adding a phosphate group to ADP 39 energy to regenerate ATP comes from catabolic reactions in the cell 39 ATP cycle energy passes during transfer from catabolic to anabolic pathways 39 Enzymes facilitate metabolic reactions 39 Catalyst chemical agent that speeds up a reaction but do not get consumed by the reaction Thursday September 24 2015 Enzyme catalytic protein 39 Activation Energy Barrier Chemical reactions between molecules are started by breaking bonds and forming new ones Activation energy the initial energy needed to start a chemical reaction 39 supplied in the form of thermal energy Enzymes reduce the activation energy required for the reaction do not effect the amount of free energy 39 speed up reactions that would have occurred without the enzyme being present 39 Substrate Specificity of Enzymes Substrate reactant that the enzyme acts on Enzymesubstrate complex what is formed when the enzyme binds to the substrate active site region where the substrate binds to the enzyme Induced t a substrate brings chemical groups to the active site that enhances their ability to catalyze the reaction 39 Enzyme s Active site the substrate binds to the enzyme s active site active site can lower an energy activation barrier by 39 positioning substrates correctly 39 straining substrate bonds Thursday September 24 2015 39 providing a favorable microenvironment 39 bonding to the substrate 39 Enzyme inhibitors 39 Competitive inhibitors bind to the active site of an enzyme changes the shape of the enzyme less effective active site 39 Noncompetitive inhibitors bind to another part of the enzyme not the active site changing the shape of the enzyme Thursday October 1 2015 BSC 2010 0001 Chapter 9 Cellular Respiration and Fermentation Six Key Concepts Metabolic pathways transfer energy through redox reactions Glycolysis begins the oxidation of glucose 39 cells make a metabolic decision after glycolysis based on 2 presence 39 When there is no 02 present cell proceeds with fermentation 39 When 02 is present cell can extract more energy from glucose 39 The breakdown of glucose to C02 is completed by the citric acid cycle 39 Oxidative phosphorylation uses the breakdown of 02 to drive ATP synthesis Cellular respiration extracts energy from macromolecules in addition to Lmht ener sugars ECOSYSTEM I I f Photosynthesis I in chloroplasts 39 CO2 H20 Organic 02 I I molecules I I Cellular respiration I in mitochondria I 5 ATP powers I most cellular work I Metabolic Pathways oxidize organic fuels to extract energy There are several processes necessary to cellular respiration and pathways Cellular Respiration Thursday October 1 2015 Redox Reactions Oxidation and Reductions The release of energy stored in organic molecules through the transfer of electrons during chemical reactions The energy released is used to synthesis ATP Redox Principle Redox reactions are chemical reactions that transfer electrons between the reactants Oxidation is the process by Which the substance loses electrons Reduction is the process by Which the substance gains electrons positive charge is reduced Example molecule of H2O molecule of O2 o o quot 39 V o O O 339 O 39 quot9 39 o 1 1 39 f o o 0 c Oxidation of Organic fuel molecules through Cellular Respiration During Cellular Respiration Fuel ex glucose is oxidized O2 is reduced Stages of Cellular Respiration ewes 1 Glycolysis break down glucose into two molecules of pyruvate Oxidation of Pyruvate begins the break down of pyruvate C39tric Acid cycle completes break down of pyruvate into CO2 Oxidative Phosphorylation ATP synthesis Pyruvate I oxidatio Acetyl CoA 39 I 1 Su bstrateIevel phosphorylation Oxidative phosphorylation electron transpo Glycolysis Glucose gt Pyruvate chemiosmosis Oxidative phosphorylation CYTOSOL Substratelevel phosphorylation Thursday October 1 2015 Glycolysis harvests chemical energy Glycolysis the splitting of sugar breaks down glucose into two molecules of pyruvate occurs in the cytoplasm and has two major phases Energy investment phase Energy payoff phase Glycolysis can occur Whether or not 02 is present NADH and pyruvate What happens to it Aerobic respiration breaks down pyruvate into C02 uses electron transport chain With 02 to generate ATP Fermentation passes electrons stored in NADH to 02 Pyruvate is not oxidized and no more ATP is produced occurs When oxygen is not present Types of Fermentation Consists of glycolysis plus reactions that regenerate NAD NAD can be reused by glycolysis Two common types Alcohol fermentation Alcohol fermentation 2 Acetaldehyde Thursday October 1 2015 lactic acid fermentation Lactic acid fermentation Glucose I Glycolysis gt 0 C0 O c39m 2 Hi 3 2 Pyruvate H 33 Pyruvate is oxidized in the presence of 02 In the Presence of 2 Pyruvate enters the mitochondria Where glucose oxidation is completed Oxidation of Pyruvate to Acetyl CoA To begin the citric acid cycle pyruvate must be converted into acetyl Coenzyme Carried out in three separate reactions Release of C02 Reduction of NAD to NADH Attachment of Coenzyme A Coenzyme A C 0 l a Pyruvate Transport protein 39 Thursday October 1 2015 The Citric Acid Cycle Completes the break down of pyruvate into C02 Genergates 1 ATP 3 NADH and FADHZ has eight steps each are catalyzed by a speci c enzyme Step 1 The acetyl group of CoA combines With oxaloacetate forming citrate Step 28 decomposes the citrate back to oxaloacetate C0 CH3 Acetyl CoA i H20 139 quot 1 2 ocKetoglutarate COOquot CH2 I i v xj c0039 3a Succinate 539 GTP GDP Succinyl H CoA ADP 2 2011 Pearson Education Inc
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