Chapter 8 HARVESTING ENERGY FROM FOOD: GLYCOLYSIS AND CELLULAR RESPIRATIONGlycolysis and Cellular RespirationC6H12O6 + 6 O2 => 6 CO2 + 6 H2O + EnergyMitochondriaCellular respiration is a cumulative function of glycolysis, the Krebs cycle, and electron transport.>>>>>Glycolysis harvests chemical energy by breaking down glucose to pyruvate Glyco=sugar Lysis=to break apart---GlycolysisPowerPoint PresentationThe reactions of glycolysis occur in two phasesSlide 10Slide 11Glycolysis is distinct from cellular respiration because:Fermentation (see fig 8-8) If there is no oxygen present then the pyruvic acid molecules from glycolysis go through fermentation - anaerobic (takes place without O2) -No ATP production -results in the partial degradation of sugars -regenerates NAD+Two types of fermentation The two most common products of pyruvate reduction are either ethanol or lactic acid. 1. Alcohol fermentation 2. Lactic acid fermentationSlide 15Slide 16How can glycolysis continue producing energy when oxygen is not present?Slide 18How is champagne different from wine?You help a friend move, and the next day, your arms and legs are sore. What caused the soreness?If there is NO oxygen around then fermentation occurs following glycolysis. If there IS oxygen around, the pyruvic acid molecules from glycolysis go to the bridge reaction, followed by the Kreb’s cycle in cellular respirationSlide 22Slide 23Slide 24Slide 25---Kreb’s CycleSlide 27The products of glycolysis and the Kreb’s cycle:Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Remember that for every molecule of glucose entering glycolysis there are two pyruvate molecules that can enter the Krebs Cycle.So where’s all the energy??---The electron transport systemElectron Transport ChainNADHSlide 41The Gas Chamber>>>>>Chemiosmosis: The energy-coupling mechanism.---Chemiosmosis is the coupling of exergonic electron flow down an electron transport chain to endergonic ATP production by the creation of a proton gradient across a membrane.Slide 45Slide 46For every NADH that feeds into the electron transport chain 3 protons are moved from the mitochondrial matrix to the intermembrane compartment. For every FADH2 that feeds into the electron transport chain 2 protons are moved from the mitochondrial matrix to the intermembrane compartment.For every proton that crosses back into the mitochondrial matrix one ATP is synthesized by ATP synthase.Overall summary of Glycolysis, the Krebs Cycle and electron transport combined.>>>>>Feedback mechanisms and control of cellular respirationChapter 8HARVESTING ENERGY FROM FOOD: GLYCOLYSIS AND CELLULAR RESPIRATIONGlycolysis and Cellular RespirationFig. 8.1C6H12O6 + 6 O2 => 6 CO2 + 6 H2O + Energy(ATP + heat)We break down glucose to CO2 and energyMitochondria•Powerhouses for the cell. Produce the cell’s ATP. •Mitochondria malfunctions can have serious consequences for an individual’s health.•More than 100 genetic mitochondrial disorders have been identified, and all lead to energy shortage, muscle weakness and chronic fatigue.Cellular respiration is a cumulative function of glycolysis, the Krebs cycle, and electron transport.Three metabolic stages of cellular respiration:1. Glycolysis2. Krebs cycle (a.k.a Citric Acid Cycle)3. Electron transport chain and oxidative phosphorylation>>>>>Glycolysis harvests chemical energy by breaking down glucose to pyruvateGlyco=sugarLysis=to break apart---Glycolysis is a catabolic pathway during which a six-carbon glucose is split into two three-carbon sugars, which are then rearranged by a stepwise process that produces two pyruvic acid molecules.---Glycolysis-Occurs in the cytoplasm-Partially oxidizes glucose (C6) in two pyruvic acid (C3) molecules-Glucose goes in, 2 pyruvic acids come out & overall 2 ATP’s are produced.CC C C C CCglucoseGlycolysis(cytoplasm) C CC2pyruvateATP2A multi-step pathway that takes place in the cytoplasm.Splits glucose to pyruvateOccurs with or without O2The reactions of glycolysis occur in two phases1. Glucose activation phase2. Energy harvest phaseglucosefructosebisphosphateATP22ADPGlucose activationCC CCC CCC CCC C-uses cellular ATP to phosphorylate (adds a phosphate group to) the glycolysis intermediates -costs two ATP molecules per glucose Fig. 8.3glucosefructosebisphosphateG3PpyruvateNAD+ADPATP22 2224 42ADPNADHATPEnergy harvestGlucose activationCC CCC CCC CCC CCC CCC C-produces ATP-yields 4 ATP molecules per glucose-2 molecules of NADH per glucoseFig. 8.3Glycolysis is distinct from cellular respiration because:•Glycolysis does not produce ATP.•Glycolysis utilizes oxygen.•Glycolysis does not occur in the mitochondria.•The products of glycolysis do not enter the mitochondria.Fermentation (see fig 8-8)If there is no oxygen present then the pyruvic acid molecules from glycolysis go through fermentation- anaerobic (takes place without O2)-No ATP production-results in the partial degradation of sugars-regenerates NAD+Two types of fermentation The two most common products of pyruvate reduction are either ethanol or lactic acid.1. Alcohol fermentation2. Lactic acid fermentationC C C C CCglucoseNADH2 ATP(glycolysis)regenerationNADHGlycolysis followed byalcoholic fermentationNAD+NAD+2 ADP(fermentation)C CC2pyruvateC C2Cethanol+ 2CO22 2 22Fig. 8.8C C C C CCglucoseNADHNAD+NADH2 ATPNAD+2 ADP(fermentation)(glycolysis)regenerationC C2ClactateC CC2pyruvateGlycolysis followed bylactate fermentation2222Fig. 8.8How can glycolysis continue producing energy when oxygen is not present? •Fermentation regenerates the NAD+ needed for glycolysis by allowing pyruvate to accept electrons and H+ from NADH.•Fermentation regenerates the ATP needed for glycolysis by allowing pyruvate to accept phosphates from ADP formation.•Fermentation produces oxygen, allowing the organism to make more energy in cellular respiration.•Fermentation keeps oxygen, which is poisonous, from entering the cell.How is champagne different from wine?Fig. 8.10How is champagne different from wine?•Both are the result of alcohol fermentation. Yeast is allowed to consume the sugars in grapes. Alcohol is produced in the process. •With wine, this process is completed BEFORE being bottled up. With champagne, the fermentation process occurs INSIDE the champagne bottle.•This produces CO2 bubbles, which pressurize inside the bottle. This is why the cork flies off when you open it.You help a friend move, and the next day, your arms and legs are sore. What
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