Bio Chapter 8 - Energy, Enzymes, and Metabolism PDF

8 Energy, Enzymes, and Metabolism © Oxford University Press Chapter 8 Energy, Enzymes, and Metabolism Learning Objectives Define “energy” Explain the difference between kinetic potential energy, and chemical energy Discuss the con...

8 Energy, Enzymes, and Metabolism © Oxford University Press Chapter 8 Energy, Enzymes, and Metabolism Learning Objectives Define “energy” Explain the difference between kinetic potential energy, and chemical energy Discuss the concepts of activation energy Define exergonic and endergonic reactions and be able to distinguish between the two. Explain the First and Second Laws of Thermodynamics as well as the concept of entropy List the basic characteristics of enzymes Describe the terms active site and substrate in regard to enzymes Describe how factors such as inhibitors influence enzyme activity Define coenzyme and cofactors © Oxford University Press Energy - Is the capacity to do work - Without energy source ALL LIFE would stop - Energy CANNOT be created - Animals gain energy from food - Algae and plants get energy from the sun - Traps energy and stores it in molecules - Then eaten as food and broken down for use in cells by consumers. - Energy cannot be created only transferred. © Oxford University Press Energy ON EXAM What’s different? Come in different forms - Potential Energy: Stored in the chemical energy bonds - Chemical Energy: Energy stored in chemical bonds - Kinetic Energy: Energy of motion or movement © Oxford University Press Figure 8.1 Energy Conversions and Work  Potential and Kinetic energy Figure 6.1 6 Chemical Transformations Involve Energy and Energy Transfers Food has potential energy stored in chemical bonds. Energy has two forms: kinetic and potential. Energy Conversions and Work Potential and kinetic Water behind a dam Waterfall Laws of Thermodynamics ON EXAM 1st law – energy is neither created or destroyed 2nd law – When energy is converted from one form to another, some of that energy becomes unavailable to do work. No energy transformation is 100% efficient; some energy is lost. Laws of energy help us understand how cells harvest and transform energy to sustain life. © Oxford University Press Figure 8.2 The Laws of Thermodynamics © Macmillan Learning Concept 8.1 Chemical Transformations Involve Energy and Energy Transfers In biological systems: - Total energy is called enthalpy (H) Enthalpy the amount of energy contained in a compound of system Entropy is a measure of disorder - Free energy (G) is the unstable energy that can do work. - Unstable energy is represented by entropy (S) multiplied by the absolute temperature (T). - H = G + TS - Change in energy can be measured in calories or joules - Change in free energy (∆G) of a chemical reaction: © Oxford University Press Energy in the body ON EXAM Endergonic reactions consume free energy Anabolism makes a single product (a highly ordered substance) out of many similar reactants (less ordered) – complexity (order) increases Endergonic Anabolism is a biochemical process in metabolism where simple molecules combine to generate complex molecules and this requires energy. Exergonic reactions release free energy Catabolism breaks down an ordered reactant into smaller, more randomly distributed products – complexity decreases (generates disorder) Exergonic catabolism break down of large organic molecules into smaller molecules this process releases energy contained in the chemical bonds. © Oxford University Press Figure 8.6 Coupling of Reactions © Macmillan Learning ATP ATP (adenosine triphosphate) captures and transfers free energy. ATP can be hydrolyzed to ADP (Adenosine diphosphate) and P1 (Inorganic phosphate), releasing a lot of energy for endergonic reactions. ATP can also phosphorylate (donate a phosphate group to) other molecules, which gain some energy. © Oxford University Press  ON EXAM Concept 8.3 Enzymes Speed Up Biochemical Transformations Catalysts increases rates of chemical reactions. The catalyst is not altered by the reactions. Most biological catalyst are enzymes (proteins) that act as a framework in which reactions can take place Catalyst - substances that regulate and accelerate the rate of biochemical reactions Some reactions are slow because of an energy barrier – the amount of energy required to start the reaction, called activation energy (Ea) Activation energy - energy required to initiate a chemical reaction. Enzymes lower the activation energy of a reaction thereby greatly speeding up the rate of the reaction. © Macmillan Learning Enzymes Accelerate Chemical Reactions (a) Without enzyme lactose glucose + galactose activation energy without enzyme net energy released from splitting of lactose (b) With enzyme lactase lactose glucose + galactose activation energy with enzyme net energy released Figure 6.9 © 2011 Pearson Education, Inc. Enzymes Speed Up Biochemical Transformations Enzymes are highly specific to the kind of reactant with which they combine Reactants are called substrates Substrate the molecule (reactant) to which they enzyme attaches itself. Enzyme substrate complex the temporary molecule that forms when the enzyme and substrate link. Substrate molecules bind to the active site of the enzyme. Active site particular site on the enzyme where the substrate binds Enzyme releases the P (product) The 3D shape of the enzyme determines the specificity. The enzyme – substrate complex (ES) is held together by hydrogen bonds, electrical attraction, or covalent bonds. E + S → ES → E + P The enzyme may change while bound to the substrate but returns to its original form. © Oxford University Press Figure 8.9 Enzyme and Substrate © Macmillan Learning Concept 8.5 Enzyme Activities Can Be Regulated Inhibitor – substance that binds to enzyme and decreases its activity Enzyme inhibitors molecules that bind to the enzyme and slow down the reaction Competitive inhibitor -- completes with substrate for active site. Competitive inhibitor cancer drug methotrexate Noncompetitive inhibitor – binds to enzyme at a site other than active site - Causes shape change that makes enzyme unable to bind substrate. Pyruvate kinase © Oxford University Press 20 Enzyme Inhibition © Oxford University Press 21  Cofactors and Coenzymes Cofactors – Inorganic ion or vitamin derivative - Assist enzymes - Can be metal ions: Zinc, molybdenum, manganese. - Often found in the active site Coenzymes – Organic molecule changes, during reaction - Cofactors that are nonprotein organic molecules - Vitamins © Oxford University Press 22  https://www.youtube.com/watch?v=qgVFkRn8f10&app=de sktop https://www.youtube.com/watch?v=UVeoXYJlBtI https://www.youtube.com/watch?v=pVoytz_3H_s https://www.youtube.com/watch?v=ueup2PTkFW8 © Oxford University Press 23  9 Pathways That Harvest Chemical Energy © Oxford University Press Chapter 9 Pathways That Harvest Chemical Energy Learning objectives Write out the overall equation for aerobic respiration. Describe the process of aerobic respiration… Glycolysis…. Identify the location of these reactions Identify the two stages and describe what occurs in each Identify the products made from this stage and where these products are sent Pyruvate Oxidation… Identify the location of these reactions Describe the conversion of pyruvate to acetyl-CoA Identify the products made from this stage and where these products are sent Citric Acid Cycle… Identify the location of these reactions Describe how the electrons move between the enzyme complexes (i.e. through the electron © Oxford University Press transport chain Cellular Respiration This energy in food is broken down and converted to Adenosine The transfer of electrons from glucose or other organic fuels to oxygen and release E(ATP) Transfer of electrons from one Triphosphate (ATP) molecules molecule to another is called oxidation and reduction or (redox) In a redox reaction the loss of electrons is called oxidation gain of electrons is called reduction. - Cells use ATP for all functions that require energy Oxidation and reduction are occurring Aerobic cellular respiration (aerobic means simultaneously. with oxygen) breaking down of glucose to make Electrons carriers like NAD (Nicotinamide lots of ATP for energy adenine dinucleotide) and FADC (Flavin adenine Consumed organic molecules are broken down and cell captures energy released in ATP dinucleotide) molecules that transfer electrons How do cells extract energy from molecules from one molecule to another involves the transfer of electrons Electron carriers such as NADH and FADH carry 2 electrons NAD+ and FAD oxidized. © Oxford University Press Respiration TOOK PICS ON MAC Aerobic Respiration requires oxygen and occurs mainly in the Mitochondria Completly breaks down Glucose Produces 36 ATP Occurs in 3 steps 1. Glycolysis 2. Citric Acid Cycle 3.Electron transport Chain © Oxford University Press Respiration: Glycolysis What is oxidation and formation of ATP Energy incestment and energy and what is happening to the energy Splits glucose into a smaller unit - 2 Pyruvate - Makes 2 ATP - 2 NADH - Occurs in the cytoplasm Energy investment phase: requires an input of energy by using 2 ATP molecules. Energy Harvest Phase: produce energy by forming 2 NADH and 4 ATP molecules Net products from 1 single glucose molecule = 2 pyruvate, 2 NADH & 2 ATP molecules 2 Pyruvates transported to the mitochondrial matrix for the next step of cellular respiration © Oxford University Press  - Recall: Glycolysis results in 2 pyruvate molecules, which are then transported to the mitochondrial matrix - Pyruvate Oxidation: 2 nd step of cellular respiration that converts each pyruvate into a molecule of Acetyl- CoA - Occurs in mitochondrial matrix and produces 2 acetyl-CoA, 2 NADH and 2CO2 molecules (per 1 glucose) © Oxford University Press  Transition Between Glycolysis and the Krebs Cycle mitochondrion glycolysis pyruvic acid to electron transport chain acetyl coenzyme A coenzyme A Krebs cytosol inner compartment cycle © 2011 Pearson Education, Inc. Figure 7.7 Aerobic Respiration: Citric Acid Cycle Krebs Cycle - Energy from electrons in pyruvate is harvested and transported to the inner membranes of the mitochondria by NADH - NAD+ molecules pick up hydrogen to transfer electrons - Produces a net 2 ATP - Occurs in the mitochondrial matrix - Releases Carbon dioxide CO2 © Oxford University Press Aerobic Respiration: Citric Acid Cycle. ON EXAM Krebs Cycle consists of a series of multiple reactions, which can be grouped into 3 phases: - Acetyl-CoA Entry: 2 carbons of Acetyl-CoA enter and react with oxaloacetate, producing citrate ”CoA does NOT enter the Krebs Cycle (just the 2 carbons enter) - Citrate Oxidation: Rearrangement and oxidation of citrate Produces of 1 ATP and 2 NADH, and 2CO2 molecules - Oxaloacetrate Regeneration: regeneration of oxaloacetate by oxidation - Produces 1 NADH and 1 FADH2 molecule 2 rounds of the Krebs Cycle occur for every 1 glucose molecule (1 round of Krebs Cycle per acetyl-CoA). © Oxford University Press Three general outcomes result from eight steps in the citric acid cycle. Anaérobic Respiration: Electron Transport Chain Occurs in the mitochondria Makes most of the ATP (32) Electrons are passed from NADH down a chain of molecules to oxygen in the mitochondrial membrane This powers the formation of ATP The oxygen combines with hydrogen to produce water © Oxford University Press  Anaerobic Respiration © Oxford University Press  Anaerobic Respiration © Oxford University Press  Anaerobic Respiration © Oxford University Press Figure 9.16 Fermentation (Part 1) © Macmillan Learning  Aerobic Respiration Overview Figure 7.5 Access the text alternative for slide images. © McGraw Hill, LLC 16  Videos https://www.youtube.com/watch?v=eBl3U- T5Nvk https://www.youtube.com/watch?v=eJ9Zjc -jdys Respiration: Glycolysis Respiration: Glycolysis  Respiration: Glycolysis Splits glucose into a smaller unit 2 Pyruvate Makes 2 ATP 2 NADH Occurs in the cytoplasm Respiration: Glycolysis  Transition Between Glycolysis and the Krebs Cycle mitochondrion glycolysis pyruvic acid to electron transport chain acetyl coenzyme A coenzyme A Krebs cytosol inner compartment cycle Figure 7.7 Three general outcomes result from eight steps in the citric acid cycle.  Aerobic Respiration: Citric Acid Krebs Cycle Cycle Energy from electrons in pyruvate is harvested and transported to the inner membranes of the mitochondria by NADH NAD+ molecules pick up hydrogen to transfer electrons Produces a net 2 ATP Occurs in the mitochondrial matrix Releases Carbon dioxide CO2 Figure 9.16 Fermentation (Part 1)  Anaerobic Respiration  Anaerobic Respiration  Anaerobic Respiration  The lack of oxygen stops Anaerobic RespirationNADH form delivering electrons to the Electron Transport System NADH donate the electron to the pyruvate from glycolysis Produces lactic acid or alcohol and CO2 Lactic acid produces the burn felt in muscles when overused Alcohol and CO2 produced by yeast and used in wine and beer  OccursAnaerobic when oxygenRespiration isn’t available Often when oxygen demand is greater than the amount of incoming oxygen The Electron transport system doesn’t have oxygen to receive electrons So, aerobic respiration stops, and anaerobic processes take over Fermentation  Anaerobic Respiration doesn’t Anaerobic Respiration require oxygen and occurs in the cytoplasm Doesn’t completely breakdown the glucose Produces only 2 ATP Occurs in 2 steps 1.Glycolysis 2.Anaerobic Respiration Chemiosmosis Aérobic Respiration: Electron Transport Chain  Aérobic Respiration: Electron Occurs in the mitochondria Transport Chain Makes most of the ATP (32) Electrons are passed from NADH down a chain of molecules to oxygen in the mitochondrial membrane This powers the formation of ATP The oxygen combines with hydrogen to produce water  Aerobic Respiration: Citric Acid Cycle Pyruvate Oxidation  Aerobic Respiration Overview Figure Access the text alternative for slide images. 39  10 Photosynthesis: Energy from Sunlight © Oxford University Press  Learning objectives Write out the overall equation for photosynthesis Describe the process of photosynthesis… Describe the importance of having a variety of pigments inside plant cells Describe where photosynthesis occurs Describe what photosystems are – what they are made of, where they are located & their function Describe the events of the dependent light cycle Describe the events of the Calvin Cycle Photosynthetic Electron Transport Chain C3 C4 and CAM plants © Oxford University Press Photosynthesis: The Big Picture ❑ 3 inputs o Sunlight o Carbon dioxide o Water ❑ 2 products o Sugar o Oxygen Photosynthesis Photosynthetic organism are considered autotrophs (specifically photoautotrophs) Photoautotrophs use light as a source of energy to produce organic molecules © Oxford University Press © Oxford University Press © Oxford University Press © Oxford University Press Photosynthesis Photosynthesis has 2 main steps: 1. Converting light energy into chemical energy 2. Uses chemical energy to make sugar from CO2 © Oxford University Press Photosynthesis: Light Dependent Reaction Is a series of energy conversions Starts with light energy Ends with chemical energy stored in covalent bonds Produces 3 chemical products ATP NADPH oxygen gas © Oxford University Press Photosynthesis: Light Reactions The first step occurs in 2 stages 1.Photosystem II Absorbs shorter wavelength of 680 nm ( more blue 2.Photosystem I Absorbs longer wavelength of 700 nm ( more red Both stages occur in the thylakoid membranes of chloroplasts © Oxford University Press Photosynthetic Electron Transport Chain Photosynthetic Electron Transport Chain Photosynthetic Electron Transport Chain Photosynthesis Is Used to Synthesize Carbohydrates (5) The Calvin cycle: Fixation of CO2 to 3PG Reduction of 3PG to G3P Regeneration of RuBP, the CO 2 acceptor For every turn of the cycle, one CO2 is fixed and one RuBP is regenerated. CO2 fixation: CO2 is reduced to carbohydrates. Occurs in the stroma. Energy in ATP and NADPH is used to reduce CO 2 © Oxford University Press The processes in the Calvin cycle occur in three steps. Concept 10.4 Plants Have Adapted Photosynthesis to Environmental Conditions (1) © Macmillan Learning Concept 10.4 Plants Have Adapted Photosynthesis to Environmental Conditions (4) C3 plants: First product of CO2 fixation is 3PG (3 carbons). On hot days, photorespiration occurs. C4 plants and Crassulacean acid metabolism (CAM): First product of CO2 fixation is oxaloacetate (4 carbons). No photorespiration on hot days. © Macmillan Learning Concept 10.4 Plants Have Adapted Photosynthesis to Environmental Conditions (5) © Macmillan Learning © Oxford University Press  https://media.hhmi.org/biointeractive/click/photosy nthesis/ https://www.youtube.com/watch?v=CMiPYHNNg2 8 © Oxford University Press