Plant Metabolism - Cell Respiration PDF

Chapter 10 Plant Metabolism FIFTEENTH EDITION James E. Bidlack, Shelly H. Jansky © 2021 McGraw Hill. All rights reserved. Authorized only for instructor use in the classroom. No reproduction o...

Chapter 10 Plant Metabolism FIFTEENTH EDITION James E. Bidlack, Shelly H. Jansky © 2021 McGraw Hill. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without Outline Introduction to Plant Metabolism Enzymes and Energy Transfer Oxidation-Reduction Reactions Photosynthesis The Essence of Photosynthesis Introduction to the Major Steps of Photosynthesis A Closer Look at Photosynthesis Other Significant Processes That Occur in Chloroplasts © Rob A. Johnston/Walkabout Wolf Photography /Getty Images Outline for Respiration, Additional Metabolic Pathways, and Assimilation and Digestion Respiration The Essence of Respiration Introduction to the Major Steps of Respiration Factors Affecting the Rate of Respiration A Closer Look at Respiration Additional Metabolic Pathways Assimilation and Digestion Introduction Photosynthesis - Converts light energy to a usable form Respiration - Releases stored energy Facilitates growth, development and reproduction Metabolism - Sum of all interrelated biochemical processes in living organisms Animals rely on green plants for oxygen, food, shelter and other products. Access the text alternative for slide images. © Ingram Publishing Enzymes and Energy Transfer Enzymes regulate metabolic activities. Anabolism - Forming chemical bonds to build molecules Photosynthesis reactions - Store energy by constructing carbohydrates by combining carbon dioxide and water Catabolism - Breaking chemical bonds Cellular respiration reactions - Release energy held in chemical bonds by breaking down carbohydrates, producing carbon dioxide and water Photosynthesis-respiration cycle involves transfer of energy via oxidation- reduction reactions. Oxidation-Reduction Reactions Oxidation - Loss of electron(s) Reduction - Gain of electron(s) Oxidation of one compound usually coupled with reduction of another compound, catalyzed by same enzyme or enzyme complex. Hydrogen atom is lost during oxidation and gained during reduction. Oxygen is usually final acceptor of electron. Respiration The essence of respiration Respiration is release of energy from glucose molecules that are broken down to individual carbon dioxide molecules. Initiated in cytoplasm and completed in mitochondria Aerobic respiration cannot be completed without oxygen. C6H12O6 + 6O2→ 6CO2 + 6H2O + energy Anaerobic Respiration and Fermentation 1 Anaerobic respiration and fermentation - carried on in absence of O2 Release less energy than that released during aerobic respiration Fermentation equations: Alcohol fermentation: C6H12O6→ 2C2H5OH + 2CO2 + ATP Lactic acid fermentation: C6H12O6→ 2C3H6O3 + ATP Introduction to the Major Steps of Respiration Glycolysis - First phase In cytoplasm, a glucose molecule becomes a fructose molecule Fructose is converted to GA3P (glyceraldehyde 3- phosphate). Energy, H, and water are removed to yield pyruvic acid Energy and H are picked up by NAD 2 ATP molecules gained. No O2 is required. Aerobic respiration, true anaerobic respiration, or fermentation may occur next. The Citric Acid (Krebs) Cycle Citric acid (Krebs) cycle - Second stage In fluid matrix of cristae in mitochondria High energy electrons and hydrogen removed as cycle proceeds. NADH, FADH2 , and small amount of ATP produced. CO2 produced as by-product. Electron Transport Electron transport - Third stage In inner membrane of mitochondria NADH and FADH2 donate electrons to electron transport system. Produces ATP, CO2 and water Anaerobic Respiration and Fermentation 2 If there is insufficient oxygen to complete aerobic respiration after glycolysis, The H released during glycolysis is transferred back to create ethyl alcohol in some organisms and lactic acid in others. Most of the energy remains locked in these molecules. True anaerobic respiration H removed from glucose is combined with an inorganic ion Oxygen is not required. Many can respire aerobically but can also go through fermentation. Glycolysis + fermentation yields 2 ATP from glycolysis Glycolysis + aerobic respiration should yield 36 ATP. Factors Affecting the Rate of Respiration Temperature When air temperature rises from 20C to 30C, respiration rates double or triple. Water Low water levels decrease respiration. Water acts as a medium for enzymatic reactions. Oxygen Flooding can reduce the oxygen supply to roots. This reduces respiration and can be fatal to plants. Crops can be stored in low oxygen conditions to minimize respiration. A Closer Look at Respiration Glycolysis reexamined Steps: Phosphorylation - Glucose becomes fructose carrying two phosphates. Sugar cleavage - Fructose split into two 3-carbon fragments: GA3P (glyceraldehyde 3-phosphate). Pyruvic acid formation - Hydrogen, energy and water removed, leaving pyruvic acid. Prior to entering citric acid cycle, pyruvic acid loses CO2 and is converted to acetyl CoA. If O2 not available, anaerobic respiration or fermentation occurs. Hydrogen released during glycolysis transferred back to pyruvic acid, creating ethyl alcohol or lactic acid. Transition Step to the Citric Acid (Krebs) Cycle After glycolysis, a molecule of CO2 is removed from pyruvate and NADH is produced before the citric acid cycle occurs. The remaining 2-carbon fragment combines with coenzyme A to form acetyl CoA. The Citric Acid (Krebs) Cycle Reexamined Acetyl CoA first combined with oxaloacetic acid, producing citric acid. Each cycle uses 2 acetyl CoA, releases 3 CO2 and regenerates oxaloacetic acid. O.A. + acetyl CoA + ADP+P+3NAD + FAD → O.A. + CoA + ATP + 3NADH + H+ + FADH2+ 2CO2 High energy electrons and hydrogen removed, producing NADH, FADH2 and ATP. Electron Transport and Oxidative Phosphorylation Energy from NADH and FADH2 released as hydrogen and electrons are passed along electron transport system. Protons build up outside mitochondrial matrix, establishing electrochemical gradient. Chemiosmosis couples transport of protons into matrix with oxidative phosphorylation: formation of ATP. O2 acts as ultimate electron acceptor, producing water as it combines with hydrogen. Produces a net gain of 36 ATP and 6 molecules of CO2 and water  A Summary of Cellular Respiration Access the text alternative for slide images. Additional Metabolic Pathways Other processes contribute to growth development, reproduction and survival. Compounds produced include: sugar phosphates nucleotides, nucleic acids, amino acids, proteins, chlorophylls, cytochromes, carotenoids, fatty acids, oils, and waxes. Secondary metabolism - Metabolic processes not required for normal growth and development Enable plants to survive and persist under special conditions Colors, aromas, poisons - Give competitive edge Codeine, Nicotine, Lignin, Salicin, Camphor, Menthol, Rubber Assimilation and Digestion Assimilation - Conversion of organic matter produced in photosynthesis to build protoplasm and cell walls Sugars transformed into lipids, proteins, or other carbohydrates, such as sucrose, starch and cellulose. Digestion - Conversion of starch and other insoluble carbohydrates to soluble forms Nearly always hydrolysis process © M Swiet Productions/Getty Images  Because learning changes everything. ® www.mheducation.com © 2021 McGraw Hill. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGraw Hill.