Cellular Respiration Continued: The Krebs Cycle and Electron Transport Chain

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<ul><li><p>Cellular Respiration Continued:The Krebs Cycle and Electron Transport Chain</p></li><li><p>Krebs Cycle aka Citric Acid CycleUses OXYGEN!! Occurs in mitochondriaAt the end of glycolysis, 90% of chemical energy in glucose is still unused. Need oxygen to remove this energy = aerobic respiration2nd stage of cellular respiration Krebs cycle (also called citric acid cycle) pyruvic acid from glycolysis is broken down into carbon dioxide in a series of energy extracting reactionsWhat comes out:2 ATPs (one for each pyruvic acid)NADH, FADH2CO2 (lots)What goes in:Pyruvic acid (from glycolysisOxygen</p></li><li><p>Steps of Krebs cycle (Citric Acid Cycle)Occurs in mitochondriaA) Pyruvic acid from glycolysis enters mitochondria. One carbon atom from pyruvic acid becomes part of carbon dioxide which is released. Two of the 3 carbon atoms are then joined to coenzyme A to form acetyl-CoA. Acetyl-CoA then adds the 2-carbon acetyl group to a 4-carbon molecule, producing a 6-carbon molecule called citric acidSummary: Pyruvic acid turned into citric acid and CO2 released</p></li><li><p>Steps of Krebs cycle (Citric Acid Cycle) (continued)B) Citric acid then is broken down into a 4-carbon molecule, more CO2 is released and electrons are transferred to energy carriers (NADH)Summary: Citric acid turned into CO2 and high-energy electrons gathered</p></li><li><p>Steps of Krebs cycle (Citric Acid Cycle) (continued)6 carbon atoms in citric acid 2 carbons removed as CO2 leaving a 4-carbon molecule which is ready to accept another 2-carbon acetyl group to start the cycle over again (leftover carbons go back into the cycle)For each turn of the cycle, an ATP is produced as well as 5 pairs of high-energy electrons captured by 5 carrier molecules 4 NADH and 1 FADH2 (similar to NADH)</p></li><li><p>Citric Acid ProductionThe Krebs CycleMitochondrion</p></li><li><p>Citric Acid ProductionThe Krebs CycleMitochondrion</p></li><li><p>Krebs CycleATP produced in Krebs cycle is then used for cellular activities. In the presence of oxygen, high energy electrons are used to generate HUGE amounts of energy in one last step</p></li><li><p>Electron Transport ChainUses OXYGEN!! Occurs in mitochondriaElectrons passed from carriers in the Krebs cycle to the electron transport chain, where the electrons are used to convert ADP to ATPWhat goes in:NADH and FADH2 (from Krebs Cycle and Glycolysis)OxygenWhat comes out:32 ATPsH2O</p></li><li><p>Steps in the Electron Transport ChainA) Electrons from NADH and FADH2 passed along to chain. In eukaryotes, the chain is located in the inner membrane of the mitochondria. High energy electrons are passed from one carrier protein to the next. At the end of the chain, electrons bind with H+ and oxygen to form water. Oxygen is final electron acceptor. (Oxygen removes used electrons)Summary: Electrons passed down chain to oxygen; water released</p></li><li><p>Steps in the Electron Transport Chain (continued)B) High-energy electrons transport H+ ions across the membrane. During electron transport, H+ ions build up on one side of the membrane = positively charged. The other side becomes negatively charged = difference in chargesSummary: During electron transport down chain, H+ brought into membrane = + charge on one side and charge on the other</p></li><li><p>Steps in the Electron Transport Chain (continued)C) Charge difference fuels ATP synthase to change ADP into ATPSummary: Use charge difference to fuel ATP production</p></li><li><p>The Electron Transport ChainElectron TransportHydrogen Ion MovementATP ProductionATP synthaseChannelMatrix</p></li><li><p>The Totals of ATP Production through Entire Cellular RespirationGlycolysis produces = 2 ATPsKrebs Cycle and electron transport chain produce = 34 ATP (Krebs Cycle produces 2 ATPs and electron transport chain produces 32 ATPs)Total = 36 ATP molecules produced</p></li><li><p>Energy and ExerciseQuick energy uses ATP quickly (sprinting) and then lactic acid kicks inLong-term energy ATP continues to be built constantly, supply the body with energy (distance running)</p></li></ul>


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