Cellular Respiration Cellular respiration is the process by which cells make energy. They use glucose and oxygen to produce carbon dioxide, water and ATP.

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  • CellularRespirationCellular respiration is the process by which cells make energy. They use glucose and oxygen to produce carbon dioxide, water and ATP (usable energy)

  • A common misconception Many people think respiration refers specifically to breathingActually respiration refers to the processes of getting energy from food.All large animals (including humans) need to use oxygen to fully release the energy from food. Thats why the word respiration has also come to refer to breathing.

  • The Summary Formula:C6H12O6 + 6 O2 6 CO2 + 6 H2O + energyGlucose + oxygen carbon dioxide + waterEnough energy is released during cellular respiration to produce up to 38 molecules of ATP38 ADP + 38 PO4 38 ATPEnergy

  • cellGlucoseOxygenCarbon dioxideWatermitochondrionEnergy (ATP)

  • Where it all happens: MitochondironATPCO2

  • Stages of Respiration:Stage 1. Glycolysis(The splitting of sugars)Stage 2. Anaerobic(The fermentation of Pyruvic Acid)Pyruvic Acid(CH3COCOOH)No oxygen availableLots of oxygen availableA little energy (2 ATP / glucose molecule)A lot of energy (38 ATP / glucose)Stage 2a. Aerobic(the Krebs Cycle)Stage 2b. Aerobic(Electron Transport)

  • Glycolysis: Splitting the sugarGlucose is split into two 3-carbon molecules called pyruvic acidThe Steps in Glycolysis are:Phosphate from ATP is joined to glucose, making a 6-carbon phosphateThe 6-C phosphate breaks into 2 PGALHydrogen is removed and phosphate added to make two 3-carbon phosphatesThe two 3-C phosphates are converted to pyruvic acid, giving off enough energy for 4 ATP

  • Glycolysis Diagram2 Pyruvic Acid (pyruvate)CH3COCOOHGlucose C6H12O6CCCCCCCCC CCC6 carbon-phosphate2 PGAL3 carbon-phosphateP-CCCCCC-PP-CCC P-CCCP-CCC-P P-CCC-P2 ATP2 ADP+P Energy used2 NAD and 2P

    2 NADH + H4 ADP+P4 ATP Energy gained

  • Uses of Pyruvic AcidThe Pyruvic acid can be used for one of several different pathways, depending on the organism and the circumstances:1. For alcoholic fermentation (in yeasts)2.For lactic acid fermentation (in milk bacteria, and emergency systems in animals)3.For aerobic respiration (the Krebs cycle) in most eukaryotes (plants and animals)In most animals, the pyruvic acid is first changed to Acetyl Co-A before being used in Krebs cycle

  • Uses of Pyruvic AcidPyruvic AcidKrebs CycleAlcoholic FermentationLactic Acid FermentationEthyl AlcoholLactic AcidAcetyl Co-ACo enzyme AEnzyme ReactionCO2CO2NADNADH+HAnaerobic RespirationAerobic Respiration2 CO2Electron TransportGlycolysis6 H2O

  • Lactic Acid Fermentation in HumansHumans normally undergo aerobic respiration (we use oxygen)Under extreme exertion (or when suffocating) we dont get enough oxygen.Then we use lactic acid fermentation to produce some energy without oxygen.Build-up of lactic acid in muscles can cause pain and cramps.Runners sometimes cant breath fast enough to supply their bodies with oxygenLactic acid build-up causes pain, fatigue, and cramps

  • Steps in aerobic respirationPyruvic acid is converted to acetyl Co-A2 carbons from Acetyl Co-A join onto a 4C compound (oxaloacetic acid) to make citric acid, a 6C compound (citric acid)Citric acid gives off one carbon dioxide to make a 5C compound (-ketoglutaric acid)This gives off another carbon dioxide to make a 4C compound (succinic acid)The 4C compound rearranged (back into oxaloacetic acid), through two intermediate steps (fumaric acid and malic acid).Captured hydrogen used to make energy

    Krebs cycle

  • The Enzyme ReactionPyruvic acid + Co-enzyme A

    CO2 + Acetyl Co-A

    Acetyl Co-A carries two carbon atoms to the Krebs cycle, before being turned back into co-enzyme A

  • Simplified Krebs Cycle DiagramCitric Acid C65-carbon compound C5(-ketoglutaric acid)4 Carbon compound C4(Succinic acid)4 Carbon compounds(fumaric acid & malic acid)Oxaloacetic Acid C4Acetyl Co-ACO2CO2NADH+HNADH+HFADFADH2NADH2OH2OC2C4

  • Advanced Krebs cycle (Optional Enrichment)Co2CO2Given offHydrogen Stored(NADH, FADH2)

  • The Electron Transport ChainAKA: cytochrome systemDuring the reactions of aerobic respiration, lots of Hydrogen has been captured in hydrogen storing compounds, including: 2 NADH from Glycolysis2 NADH from conversion of Pyruvic Acid6 NADH from the Krebs cycle2 FADH2 from the Krebs cycleMany of the hydrogens have lost electronsNow the energy of those electrons & hydrogen ions are used to make ATP

  • The Electron Transport Chain

  • The Electron Transport ChainAlong the inner membrane of the mitochondrion, electrons are passed from molecule to moleculeThe energy from these electrons is used to pump hydrogen ions (H+) into the space between the membranesThe hydrogen ions diffuse back in, producing ATP by chemiosmosis (similar to photosynthesis)The hydrogen ions and electrons are combined with oxygen to form water.

  • The Electron Transport ChainThe simplified outcome of electron transport:The hydrogen atoms join with oxygen to make water.Lots of ATP is produced4 H+ + O2 +4e- H2O + EnergyENERGY

    ATPADP + P

  • Remember, up to 38 ATP molecules can be produced from the complete respiration of a single glucose molecule. Other organic molecules, such as starches and lipids, can produce even more ATP if they undergo complete respiration.ATP is the energy exchange medium of the cell. It provides the energy for most cellular activity.

  • Cellular Respiration VideosCellular Respiration (Overview Lecture)Sugar Goes to ATP (Hey There Delilah)Cellular Respiration Song ( I Gotta Feeling)Cellular Respiration (Californication: too long for class)Student Made Respiration video (not too bad)Student-made Respiration song (dreadful and full of spelling mistakes, but mercifully short)

  • Assignments on Respiration.Read Chapter 7, pp. 127 to 138.Read carefully the chapter summary on page 139.Do exercises on page 140 # 1 to 20Draw a diagram to represent the Krebs cycle


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