Cellular Respiration Producing ATP from the energy in food

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  • Cellular RespirationProducing ATPfrom the energyin food

  • An OverviewATP is immediate source of energy used by cellsEnergy in ATP held in phosphodiester bondsMost energy release in cells results from redox rxns. involving GlucoseC6H12O6 + O2 --> 6 CO2 + 6 H2O + energy

  • 40% of energy in Glucose is converted to usable energy in ATPProduction of ATP and other organic molecules is endergonic and require a constant input of energy to continue.The source of that energy is the sun.Photosynthesis is essentially the opposite of Cellular Respiration.Energy flows from sun to autotrophs to heterotrophs.All energy is lost eventually as work or heat.

  • Cellular RespirationTHE BEGINNING*GLYCOLYSIS

  • GlycolysisActivation of Glucose1 ATP used to add P to Glucoseforms Glucose PhosphateFructose Phosphate then formed1 ATP - P = 1 ADP + P

  • Formation of Sugar Diphosphate1 ATP used to add P to Fructose PhosphateForms Sugar Diphosphate (sugar and two Ps)1 ATP - P = 1 ADP + P

  • Formation and Oxidation of G3PSugar Diphosphate (6 C) into two 3 C molecules1 into G3POther 3 C becomes a different 3 C, but is then converted into G3PBoth G3Ps lose an HAccepted by NAD to make 2 NADHsHigh energy level e-s carried by the HsSome of the energy used to make 2 ATPs

  • Formation of Pyruvate3 more reactions make two Pyruvate moleculesThe energy released from these reactions used to make 2 ATPsTwo C3H4O3 = 6 Cs, 8 Hs, 6 Os (just 4 Hs removed from Glucose, C6H12O6.

  • Summary of GlycolysisGlucose split into two 3 Cs2 ATPs used for activation energy2 molecules NADH produced (+ 2 H+)4 ATPs made (net gain of 2 ATPs)Pyruvate is the 3 C madeWill next enter Krebs Cycle if Oxygen is availableWill undergo fermentation if no Oxygen is availableOccurs in cytoplasmNo oxygen required (but can be present)

  • The Oxidation of PyruvateA necessary first step prior toeitherThe Citric Acid Cycle or Fermentation

  • Oxidation of Pyruvate2 e - and their associated H released1 e - from each PyruvateAccepted by 2 NADs to form 2 NADHs A C also released from each pyruvateforms two CO2sResults in formation of two acetyl groups

  • The Citric Acid CycleOccurs in mitochondriaAn aerobic processBegins with acetyl (or Pyruvate if you include the oxidation of pyruvate as part of this process)Ends with CO2 ,H2O, NADH and FADH2 and some ATP being produced

  • The processAcetyl groups combine with a coenzyme the coenzyme is CoAjust hanging around in mitochondriaforms AcetylCoAAcetylCoA joins a 4C compound already present The 4 C is oxaloacetic Acidforms Citric Acid (6C)Citric Acid undergoes two rxns to form isocitric acid

  • Isocitric Acid is oxidizedThe Hs released are accepted by NAD and FADforms 4 NADH and two FADH2some of the energhy used to form two more ATP moleculesForms Fumaric AcidFumaric Acid undergoes 2 rxnsForms Oxaloacetic AcidCombines with AcetylCoA to form Citric AcidThe whole darn thing happens again!Two more NADHs produced

  • 2NADH produce in the Oxidation of Pyruvate2ATPs produced in Citric Acid Cycle6 NADH and 2 FADH2 also produced in Citric Acid CycleAdd that to the net gain of 2 ATP and 4 NADH produced in glycolysis4ATP10 NADH2 FADH2

  • Electron Transport ChainUtilizing the energy held in NADH and FADH2 previously produced to make ATPProduced by chemiosmosis Gradient produced b/w the area within the inner and outer mitochondrial membrane and inside the mitochondria2 NADH from glycolysis were actively transported in (required 1 ATP each)

  • The ETCHigh energy e - s carried by NADH and FADH2 transported out of inner mitochondrial membrane into area b/w inner and outer membrane by cytochromes embedded in the membrane.protons followe - accepted by Oxygen to form H2Ocreates proton conc. gradientProtons move back across membrane in response to gradientMovement coupled to production of ATP

  • The Balance Sheet from ETCEach NADH drives synthesis of 3 ATP10 NADH from glycolysis, oxidation of pyruvate and the citric acid cycle30 ATPbut the NADHs from glycolysis cost 1 ATP each to transport (- 2 ATP)Each FADH2 drives synthesis of 2 ATP2 FADH2 s from Citric acid cycle4 ATPNet gain from ETC = 32 ATP

  • Overview of Oxidative MetabolismGlycolysis2ATP (net gain), 2 NADHanaerobic, in cytoplasmOxidation of Pyruvate2 NADHCitric Acid Cycle2ATP, 6 NADH, 2 FADH2aerobic, in mitochondriaETC32 ATP (net gain), H2O in christae of mitochondria

  • FermentationAnaerobic Respiration:allowing Glycolysis tocontinue without O2

  • Alcoholic FermentationPyruvate from glycolysis is oxidizedforms acetylCO2 also formedAcetyl combines with H from NADH (from gly)forms ethyl alcoholalso forms NAD to be used in glycolysisAlcohol becomes toxic @ 12 %ceases fermentationthats why fermented drinks have max alcohol of 12%Uses: wine, brewing, baking

  • Lactic Acid Fermentation Pyruvate from glycolysis doesnt get oxidizedan enzyme helps to bond H from NADH to pyruvateforms Lactic Acid - Ooooh feel the burn!makes NAD available for glycolysis to continueOccurs in aerobic cells under O2 stress - muscleAlso occurs in certain other microorganismssour cream, yogurtvinegar


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