BIO 1010 Unit 4 Chatper 4 Metabolism PDF

Metabolism Chapter 4 BIO 1010 DOLAN UNCP Chapter 4 Learning Objectives Relate the transfer of electrons (or hydrogen atoms) to the transfer of energy. Define photosynthesis and describe how photosynthesis is important not only to plants but to the entire web of life on Planet Earth. Write a summary...

Metabolism Chapter 4 BIO 1010 DOLAN UNCP Chapter 4 Learning Objectives Relate the transfer of electrons (or hydrogen atoms) to the transfer of energy. Define photosynthesis and describe how photosynthesis is important not only to plants but to the entire web of life on Planet Earth. Write a summary reaction, explaining the origin and fate of each compound involved. Summarize the events of the light-dependent reactions of photosynthesis, including the role of light in the activation of chlorophyll. Describe how a proton gradient allows the formation of ATP according to the chemiosmotic model. Summarize the events of the carbon fixation reactions of photosynthesis. Write a summary reaction for aerobic respiration, giving the origin and fate of each substance involved. List and give a brief overview of the 4 stages of aerobic respiration. Distinguish between alcohol fermentation and lactic acid fermentation. Life in the Sun Light is central to the life of a plant Photosynthesis is the most important chemical process on Earth – It provides food for virtually all organisms Feeding Types (Trophic Types) Photoautotrophs (producers) – Require light, CO2, minerals, water Chemoautotrophs (producers) – Produce organic matter without the help of light Heterotrophs (consumers) – Obtain organic matter by consuming others – Dependent on autotrophs for food Photosynthetic Organisms garden plants mosses trees diatoms kelp Euglena cyanobacteria Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5 (Moss): © Steven P. Lynch; (Trees): © Digital Vision/PunchStock; (Kelp): © Chuck Davis/Stone/Getty Images; (Cyanobacteria): © Sherman Thomas/Visuals Unlimited; (Diatoms): © Ed Reschke/Peter Arnold; (Euglena): © T.E. Adams/Visuals Unlimited; (Sunflower): © Royalty-Free/Corbis Enzymes and Energy Transfer Enzymes regulate metabolic activities. – Anabolism - Forming chemical bonds to build molecules PS - Store energy by constructing carbohydrates from combos of CO2 and H2O – Catabolism - Breaking chemical bonds Cellular respiration (CR) - Release energy held in chemical bonds by breaking down carbohydrates, producing CO2 and H2O – Photosynthesis & Respiration cycle involves transfer of energy via reduction-oxidation (redox) rxns. Photosynthesis and Cellular Respiration (aerobic) Relationship The Energy Dispenser: ATP Adenosine Triphosphate the most important energy transfer molecule in living things. The ATP/ADP Cycle Phosphorylation: – Adding the Phosphate group back, ADP  ATP Energy is stored Dephosphorylation: – Loosing the outermost phosphate group, ATP  ADP (adenosine diphosphate) Energy is released Enzymes and Energy Transfer Oxidation-reduction reactions (Redox) – Oxidation - Loss of electron(s) – Reduction - Gain of electron(s) Usually a coupled rxn Hydrogen atom (H+) is lost during oxidation and gained during reduction. – Often referred to as a proton (H+) Oxygen is usually final acceptor of electron. Reduction-Oxidation (redox) reactions: Coupled reaction where electrons pass from one molecule to another Hydrogen atom (H+) is lost during oxidation and gained during reduction. Reduction-Oxidation (redox) reactions: https://youtu.be/lQ6FBA1HM3s AN OVERVIEW OF PHOTOSYNTHESIS Photosynthesis in plants 1. takes place in chloroplasts, 2. converts carbon dioxide and water into organic molecules 1. Organic molecules are used for energy, storage, biomass accumulation, etc 3. releases oxygen. The Nature of Sunlight – Sunlight = aka Radiation, or electromagnetic energy. Light also acts like discrete particles = photons – Electromagnetic spectrum = full range of radiation Increasing wavelength 10–5 nm 10–3 nm 1 nm 103 nm 106 nm Gamma rays X-rays UV 1m MicroInfrared waves 103 m Radio waves Visible light 380 400 500 Wavelength (nm) 600 Wavelength = 580 nm Figure 7.4 700 750 Photosynthesis 40% of Earth’s radiant energy from the sun visible light. – Violet to blue & red-orange to red wavelengths are used more extensively. – Green light is reflected. Only 80% of visible light is absorbed. Light intensity varies with time of day, season, altitude, latitude, and atmospheric composition. Photosynthesis  Plants vary considerably in light intensities needed for optimal photosynthetic rates.  Temperature and amount of carbon dioxide can also be limiting. Photosynthesis Tolerance ranges and optimum of light & temperatures – too high = changes in leaf carbon dioxide:oxygen. – Accelerates Photorespiration Uses oxygen and releases carbon dioxide Helps some plants survive under adverse conditions Extreme light intensity = Photooxidation occurs, which results in destruction of chlorophyll. Too much light causes the closing of stomata, – Limiting the available carbon dioxide for PS Photosynthetic Pigments Chlorophyll a: Participates directly in PS Accessory Pigments: – Chlorophyll b Indirect participation in PS Transfer energy to chl a – Carotenoids, Xanthophylls Indirect participation in PS Transfer energy to chl a Stage and Casting Where does the photosynthesis play happen? Who are the characters? Additional Background Information Where does Photosynthesis happen? Internal Leaf Anatomy is arranged to maximize the interception of light and gas exchange Chloroplasts – Site of Photosynthesis Thylakoid Membranes (Light Reaction) Grana – stacks of thylakoids Thylakoid Lumen Stroma – fluid outside thylakoids (Calvin Cycle) Light Reflected light Chloroplast Absorbed light Transmitted light Chloroplast Anatomy Photosystems: Light Antenna Embedded in the thylakoid membranes Grouped pigments acting as a lightgathering antenna. Harvest light energy Photosystems Photosystem II First in process AKA P680 Water Splitting photosystem Photosystem I Second in process AKA P700 NADPH producing photosystem How Photosystems Harvest Light Energy (Z-diagram) NADP+ (NADPH) – Electron carrier Nicotinamide adenine dinucleotide phosphate Free floating agent in stroma Transports energy (electrons) to Calvin Cycle – Prius Airport Taxi (oxidized) (reduced) Electron Transport Chain (ETC) Series of embedded transport proteins Between PS II and PSI & After PS I Transfer excited electrons, pump protons (H+), reduce NADP+ to NADPH H+ H+ ATP Synthase ATP producing enzyme Embedded in thylakoid membrane Photophosphorylates ADP + P  ATP – Uses proton gradient – Chemiosmosis Photosynthesis: Light-Dependent Reactions Chemiosmosis – Net accumulation of protons in thylakoid lumen Source: split water and e transports – ATPase moves protons form lumen to stroma. – Movement of protons across membrane = source of energy for synthesis of ATP Chemiosmosis (part of the electron transport chain) High H + concentration H+ H+ H+ H+ H + pump in electron transport chain H+ ADP + P ATP synthase complex energy from electron transfers H+ Low H + concentration 31 H+ ATP Review Questions Why is photosynthesis important? Which organisms complete photosynthesis? Where does it happen? Where does water and gas exchange occur? Primary pigment? Accessory Pigments? Light harvesting antenna complex? Enzyme used to make ATP? Electron Carrier? REDOX reactions? Electron Transport Chain? The Overall Equation for Photosynthesis (PS) Water is split into: Carbon dioxide harvested from air and reduced – Hydrogen, Oxygen, Electrons Energy stored as Sugar (C6H12O6) Electrons energized Oxygen released by sun Water is consumed & Electron Carriers produced reduced PS: Two Step Process 1. Light Reaction (photo) – thylakoid membranes Interception of light energy & transferred to ATP & NADPH H 2. Calvin Cycle (synthesis) - stroma – ATP and NADPH used to create sugars – aka Light independent, Dark Reaction PS: Two Step Process Summary 1. Light Reactions: light energy  chemical energy. – Harvest and transfers lights energy – Water is spilt (photolysis) & energized electrons transferred – Reactants: H2O, ADP, P and NADP+ – Products: NADPH, ATP, NO SUGAR produced 2. Calvin Cycle - uses the energy from the light rxn to: – Incorporates CO2 from air into organic molecules – Powered by NADPH and ATP – Reactants: ATP, NADPH, RuBP – Products: Glucose, ADP, P and NADP+, RuBP Light Reactions: Overall Process Electron Transport Chain Electron Transport Chain 4 2 3 1 6 5 See the next two slides for descriptions of the blue numbers Light Reaction Steps (follow diagram #s) 1. Solar energy is intercepted by PS II, H2O is split releasing O2, H+ and e’s – Is a waste product, e’s are passed into PS II and are energized by solar energy, H+ remain in thylakoid lumen 2. Energized electrons are passed to the ETC, – the energy is used to pump H+’s from the stroma against the concentration gradient to build up the H+ ions in the thylakoid lumen Light Reaction Steps (follow diagram #s) 3. De-energized e’s are passed to PS I to be reenergized by solar energy 4. Re-energized e’s are passed to 2nd ETC – Energy used by NADPH Reductase to reduce NADP+ into NADPH 5. H+ built up in the thylakoid lumen begin to diffuse through ATP synthase. – ATP synthases uses the kinetic energy of falling H+ to photophosphorylate ADP and P into ATP Known as Chemiosmosis 6. ATP and NADPH enter the Calvin Cycle Photosynthesis: Light-Dependent Reactions PS: Two Step Process 1. Light Reaction (photo) – thylakoid membranes – Interception of light energy & converted to ATP H 2. Calvin Cycle (synthesis) - stroma – ATP and NADPH used to create sugars – aka Light independent, Dark Reaction Calvin Cycle Reactions: Overview of C3 Photosynthesis A cyclical series of reactions Utilizes atmospheric CO2 to produce carbohydrates Known as C3 photosynthesis Involves three stages: 1. Carbon dioxide (CO2) fixation 2. Carbon dioxide (CO2) reduction 3. RuBP regeneration (ribulose-1,5-bisphosphate) 44 The Calvin Cycle 6 CO2 6 C6 1 2 12 3PG C3 6RuBP C5 12 ATP 12 BPG C3 6 ATP 10 G3P C3 3 12 G3P C3 12 NADPH Glucose or other organic molecule 2 G3P C3 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 12 NADP+ Calvin Cycle Reactions: Step 1. Carbon Dioxide Fixation 6 CO2 is attached to six 5-carbon RuBP molecule – Each results in an unstable 6-carbon molecule – Unstable 6-carbon molecule splits into two 3-carbon molecules (3PG) – Reaction accelerated by RuBP Carboxylase (Rubisco) CO2 now “fixed” b/c it is part of a carbohydrate 46 Calvin Cycle Reactions: Step 2 - Carbon Dioxide Reduction 3PG reduced to BPG ATP ADP + P BPG reduced to G3P 3PG Utilizes NADPH and some ATP that was produced in light reactions BPG NADPH G3P NADP+ As 3PG becomes G3P, ATP becomes ADP + P and NADPH becomes NADP+ 47 Calvin Cycle Reactions: Step 3 - Regeneration of RuBP Must replace the RuBP used in CO2 fixation Ten G3P (a 3-carbon molecule) used to remake 6 RuBP (a 5-carbon molecule) – 10 X 3 => 30 C3 plants in hotter, drier climates Disadvantage: Not at as productive as C3 plants in cooler, moister climates ALTERNATIVE PHOTOSY C4 Pathway (example: sugarcane) Mesophyll Cell and Chloroplast Distribution in C4 vs. C3 Plants C3 Plant C4 Plant mesophyll cells bundle sheath cell vein stoma bundle sheath cell Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. vein stoma 58 Mesophyll Cell Distribution in C3 vs. C4 Plants C3 Plant C4 Plant bundle sheath cell bundle sheath cell vein 59 Photosynthesis: C4 Photosynthesis Pathway – CO2 converted to organic acids in mesophyll cells. PEP (phosphoenolpyruvate) + CO2 combine, with aid of PEP carboxylase. – Form oxaloacetic acid (4C), instead of 3PG – Oxaloacetate (4C)  Malate (4C) – Malate (4C) is transported to the bundle sheath cells – Enters the Calvin cycle Photosynthesis: C4 Photosynthesis PEP carboxylase converts CO2 to carbohydrate at lower CO2 concentrations than does Rubisco. o Not sensitive to O2, no photorespiration o – Net productivity ~2-3X > C3 plants in hot, dry environments At low temperatures, C3 more efficient –. o Costs 2 ATP for C4 photosynthesis. C4 Plants ALTERNATIVE PHOTOSYNTHETIC PATHWAYS CAM Pathway C4 Pathway (example: sugarcane) (example: pineapple) Corn Cell type 1 CO2 Four-carbon compound Cell type 2 CO2 CO2 Night Four-carbon compound CO2 Millet Climate Driven Evolution: CAM Plants Crassulacean-Acid Metabolism – Are adapted to extremely dry climates – Open their stomata only at night to conserve water – During the night fix CO2 = C4 molecules, Stored in Vacuole – During daylight NADPH and ATP are available Stomata closed for water conservation C4 molecules release CO2 to Calvin cycle Photosynthesis: CAM Plants CAM = Crassulacean-Acid Metabolism – Similar to C4 photosynthesis with 4C compounds made during light rxns, but…. @ Night = Organic acids accumulate and are stored in vacuole Stomata open @ Day = converted back to CO2 to use in Calvin cycle Stomata closed More efficient when water is low but light is high. – CAM Plants Photosynthesis  Plants vary considerably in light intensities needed for optimal photosynthetic rates.  Temperature and amount of carbon dioxide can also be limiting. Other Significant Processes in the Chloroplast Reduction of sulfate to sulfide – Sulfides used to make amino-acids – Methionine and Cystine Important in synthesis of proteins, anthocyanins, chlorophylls and others Nitrates converted to ammonia – Ammonia used to make amino-acids, for eg-Glutamine stored in roots and specialized stems Important storage mechanisms for nitrogen Photosynthesis may moderate global climate change Global Climate Change caused by increasing CO2 levels may be reduced by: – limiting deforestation – reducing fossil fuel consumption – growing biofuel crops that remove CO2 from the atmosphere. © 2012 Pearson Education, Inc. Cellular 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 w/o O2. – C6H12O6 + 6O2 6CO2 + 6H2O + energy Glucose Breakdown: Summary Reaction Oxidation C6H12O6 + glucose 6O2 6CO2 + 6H20 + Energy (ATP) Reduction  Electrons and H+s are removed from substrates and received by oxygen, which combines with H+ to become water.  Glucose is oxidized and O2 is reduced  1 glucose = up to 36-38 ATP 72 Aerobic Respiration: Major Steps of Respiration 1. Glycolysis - First phase     In cytoplasm No O2 required. Glucose converted to GA3P (glyceraldehyde 3-phosphate). 2 ATP molecules gained. 2. Pyruvate Oxidation (Formation of Acetyl CoA)  In mitochondria  Pyruvate (3C) degraded to Acetyl CoA (2C)  Releases carbon dioxide as a by-product  NAD+ reduced to NADH  electron transport chain Aerobic Respiration: Major Steps of Respiration 3. Citric acid (Krebs) cycle  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. 4. Electron transport  In inner membrane of mitochondria  NADH and FADH2 donate electrons to electron transport system.  Produces ATP, CO2 and water Glucose Breakdown: Overview of 4 Phases 75 Aerobic Respiration: Glycolysis – 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. Glucose Breakdown: Overview of 4 Phases 78 Aerobic Respiration: Pyruvate Oxidation – Occurs in the mitochondria matrix – Reactants: 2 pyruvate, 2 Coenzyme A – Products: 2 Acetyl CoA, 2 NADH, 2 CO2 Pyruvate is oxidized and binds with Coenzyme A NAD+  NADH Carbon removed from Pyruvate  CO2 =waste 2 Pyruvate CoA CoA 2 NAD+ 2 NADH 2 CO2 CoA CoA 2 AcetylCoA Glucose Breakdown: Overview of 4 Phases 80 Aerobic Respiration: Citric Acid Cycle aka Krebs cycle or TCA cycle – 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. Citric Acid Cycle Glucose Breakdown: Overview of 4 Phases 83 Aerobic Respiration: Electron Transport Chain 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 Figure 6.10 H Intermembrane space H H H H Mobile electron carriers Protein complex of electron carriers H ATP synthase IV I II FADH2 Electron flow NADH Mitochondrial matrix H H III Inner mitochondrial membrane H NAD FAD 2 H 1 2 O2 H2O H ADP P ATP H Electron Transport Chain Oxidative Phosphorylation Chemiosmosis Respiration Carbohydrate Catabolism The oxidation of glucose to form ATP... Glucose (C6H12O6) + O2  CO2 + H2O + ATP Cellular Respiration BIO FLIX Anaerobic Respiration (Fermentation) Occurs in the absence of O2 – Much less efficient than aerobic respiration Only 2 ATPs produced. – Fermentation equations: C6H12O6 2C2H5OH (ethanol) + 2CO2 + ATP C6H12O6 2C3H6O3 (lactic acid) + ATP Fermentation (w/o O2) An anaerobic process reduces pyruvate to… Lactate or, Alcohol and CO2 NADH passes its electrons to pyruvate Lactic acid fermentation Certain bacteria and fungi produces lactic acid (lactate) Production of cheese, yogurt, and sauerkraut. Alcoholic fermentation Yeasts Carbon dioxide and ethyl alcohol Production of alcoholic spirits and breads. CR-1 Fermentation Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. CR-1 Factors Affecting the Rate of Respiration Temperature – Increase from 20o C to 30o C, respiration rates double. Water – Medium in which enzymatic reactions take place – Low water content - Respiration rate reduced. Oxygen – Reduction in oxygen - Respiration and growth rates decline. 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 Questions??? Molecular Formula Version of the Calvin Cycle Start Here (3PGA) (3PGA) Fixation Reduction RuBP Regeneration (GA3P) Molecular Formula Version of the Citric Acid Cycle Photosynthesizing Animals? Elysia chlorotica What the what? A sap sucking, solar powered sea slug!!! https://www.youtube.com/watch?v=pAMP8erryKE