Section 2, chapter 4

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Text of Section 2, chapter 4

  • 1.Section 2, Chapter 4

2. Overview of Cell RespirationInitial fuel or energy sourceATP = energy currency used by cellsGlucose is broken down to make ATPOxidation- transfer of electrons away from a molecule. Glucose is oxidized in cell respiration. Energy from the transfer of e- away from glucose is used to make ATP. 3. Cells break down ATP into ADP for cell activity.Adenosine Triphosphate (ATP)Adenosine Diphosphate (ATP)Currency of Energy for cellsATP is converted to ADP by hydrolyzing one of the phosphorus bondsADPATP hydrolysisEnergy is released by hydrolyzing 3 rd phosphate group of ATP 4. Cells quickly use their ATP supplies for cell activity, so the ATP must be replenished.Cell respiration regenerates ATP supplies by adding a phosphate to ADP 5. ATP provides energy for cell activityCell Respiration regenerates ATPFigure 4.8 6. Cell Respiration anaerobic respiration (glycolysis) occurs in the cytoplasm does not require oxygen yields 2 ATP per glucoseaerobic respiration occurs in mitochondria requires oxygen yields up to 38 ATP per glucose 7. Cell Respiration involves 3 reactions 1. Glycolysis Glycolysis is a series of anaerobic reactions that occur in the cytoplasm. Glucose is broken down into 2 molecules of pyruvic acid Only 2 molecules of ATP are produced per glucose molecule.2. Citric Acid Cycle (Krebs Cycle) If oxygen is present respiration continues into the Citric Acid Cycle within the matix of the mitochondrion.3. Electron Transport Chain Aerobic respiration is complete in the electron transport chain. ETC occurs on the inner membrane of the mitochondrion. 8. Overview of Cell Respiration2 ATP If O2 availableglucose1. glycolysisWithout O2Lactic acid2. citric acid cycle3. ETCUp to 36 ATP 9. Overview of Cell Respiration cellglucosemitochondrion 1. Glycolysis (anaerobic )pyruvic acidO2 available pyruvic acidO2 not available Lactic acid2. CAC3. ETC 10. Electron Carriers: NADH & FADH2 During respiration electrons are removed from glucose and transported to the ETC by electron carriers. Energy from the electrons is used to synthesize ATP in the ETC.glucose2e-2e-NAD+NADH2e-FADFADH2NADH carries 2e- from glucose into the ETC, where its worth 2-3 ATPFADH2 carries 2e- into the ETC, where its worth 2 ATP 11. Glycolysis Glycolysis breaks down glucose into 2 Pyruvic Acid molecules Occurs in Cytoplasm of Cell Anaerobic Reaction (no oxygen required) Glycolysis Yields 2 ATP (net gain) per glucose 2 NADH molecule (worth 2-3 ATP in the ETC) 2 Pyruvic Acid molecules 12. glucoseSummary of Glycolysis Phase 1: phosphorylation of glucoseATP ADP2 phosphates are added to glucose. 2 ATP are hydrolyzed into 2 ADP molecules in this step.ATP ADPPhase 1Phase 2Phase 2: lysing of glucose Glucose is split into 2 3-carbon molecules 2ADP 2 ATPPhase 3: oxidation of glucose glucose is oxidized into 2 molecules of pyruvic acid Phase 3 produces 4 ATP, 2 NADH 2 molecules of pyruvic acid.2ADP 2ATPPhase 3 NAD+NAD+NADHNADHpyruvic acidpyruvic acid 13. +4 ATP are produced in the third phase - 2ATP are used in the first phaseGlycolysis produces a net gain of 2 ATP The overall products of glycolysis includes: 2ATP 2 Pyruvic Acids 2 NADH (these carry e- to the ETC) 14. pyruvic acid If O2 is not available pyruvic acid completes anaerobic respiration in the cytoplasm.If O2 is available pyruvic acid enters mitochondria for aerobic respiration. 15. Anaerobic Respiration The electron carriers (NADH) from glycolysis cannot enter into the ETC if oxygen is not available. Without oxygen NADH donates its electrons to pyruvic acid, forming Lactic acid. 2e-NADHNAD+ 2e-pyruvic acidlactic acidThis replenishes NAD+ supplies, so they can be used to remove electrons from additional glucose molecules. 16. Anaerobic Respiration Without O2, Lactic acid builds up as glucose is burned During exercise when there isnt sufficient O2 for aerobic respiration, lactic acid (Lactate) accumulates in the cells. 17. Anaerobic Respiration Once oxygen is available (eg after exercise), then Lactic Acid is converted back to glucose by the liver Oxygen debt is the amount of O2 required to convert the lactic acid back to glucose after exercise. Anaerobic respiration yields only 2 ATP per glucose, but it provides cells with a quick source of energy; for exerciseEnd of section 2, chapter 4