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Cellular Respiration Ch. 8

Cellular Respiration Ch. 8. How we get Energy from Light. Cellular respiration is just a series of steps where energy is transfer between different molecules through a flow of electrons The ultimate goal is to produce ATP The initial start of the process is light during photosynthesis

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Cellular Respiration Ch. 8

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  1. Cellular RespirationCh. 8

  2. How we get Energy from Light • Cellular respiration is just a series of steps where energy is transfer between different molecules through a flow of electrons • The ultimate goal is to produce ATP • The initial start of the process is light during photosynthesis • What is the final acceptor of the electrons used to make ATP? • Oxygen • Combines with H+ to make water

  3. OIL RIG • OIL Oxidized if lose (electrons) • Electron donor • Decrease in positive electric charge • RIG Reduced if gain (electrons) • Electron acceptor • Increase in positive electric charge • What types of reactions have this occur? • Redox reaction • Not all redox have complete exchange of electrons • Figure 8.2 • Moving electrons closer or further from the central atom shows change in energy • Carbon partially lost electrons • Oxygen partially gained

  4. Steps of Cellular Respiration C6H12O6+ 6O2+ 32ADP+ 32Pi 6H2O+ 6CO2+ 32 ATP • 3 steps: • Glycolysis • Glucose is broken into 2 pyruvate molecules • Pyruvate Oxidation and Citric Acid Cycle • Pyruvate is made into Acetyl-CoA and enters a reaction cycle • Oxidative Phosphorylation • Electron transporter molecules move to the inner mitochondria membrane and generate ATP

  5. Glycolysis Glucose+ 2ADP+ 2Pi + 2 NAD+ 2Pyruvate+ 2NADH+ 2H++ 4ATP • 10 enzymes are required • Steps 1 and 3 hydrolysis ATP to build instability and power breaking of glucose to G3P (glyceraldehyde-3-phosphate) • Electron carrier NAD+ (nicotinamide adenine dinucleotide) is reduced to NADH • Step 7 dephosphorylates C-1 to make ATP (2x) • Step 9 releases H2O • Step 10 dephosphorylates C-3 producing ATP and Pyruvate (2x) • What produce to respiration do we not see yet? • CO2

  6. Regulation of Glycolysis • What molecule would best regulate glycolysis? • ATP levels • If ATP levels are high, phosphofructokinase in step 3 • What else could regulate it? • NADH levels • Why does alcohol make you fat? • Breaking down alcohol boosts NADH levels in liver cells • NADH stops glycolysis so sugars are converted to glycogen • Alcohol enters Citric acid cycle as acetyl-CoA • Prolonged high NADH levels and extra acetyl-CoA create fatty acids which get stored in adipose cells (fat cells)

  7. Pyruvate Oxidation 2Pyruvate+ 2CoA+ 2NAD+ 2acetyl-CoA+ 2NADH+ 2H++ 2CO2 • Active transport pulls pyruvate into the mitochondrial matrix • -COO- is removed as CO2 • 2-C acetyl binds to coenzyme A to make acetyl-CoA; which can enter the citric acid cycle • 2 electrons are also passed on to NADH

  8. Citric Acid Cycle (Krebs Cycle) 1Acetyl-CoA+ 3NAD++ 1FAD+ 1ADP+ 1Pi+ 2H2O 2CO2+ 3NADH+ 1FADH2+ 1ATP+ 3H++ 1CoA • 8 reactions in a cycle convert acetyl-CoA into CO2 and recycle the CoA • Steps 1 and 7 need H2O • Steps 3 and 4 release CO2 • Steps 3, 4, and 8 release NADH • Step 6 releases FADH2(flavin adenine dinuclotide) • Cycle runs twice for each glucose used • What can inhibit the cycle? • ATP levels

  9. Alternative Energy Sources • Triglycerides (fats) are hydrolyzed into glycerol and then G3P (step 6 in glycolysis) • Triglycerides (fats) are broken into 2-C units and bind with CoA • Fats are great source of energy but take longer to breakdown • Proteins are broken into AA and then change into pyruvate or an intermediate step in the citric acid cycle

  10. Oxidative Phosphorylation • Electron Transport Chain • All NADH/FADH2 bring collected electrons/protons to the inner mitochondrial membrane • Protein complexes I-IV use Cytochrome C and Ubiquinone to transfer electrons through the system • The energy released actively pumps H+ outside of the matrix • Concentration gradient powers ATP synthase like water powers a turbineto make ATP

  11. The Complexes • Complexes I, III, and IV use cytochrome c and coenzyme Q (ubiquinone) to move electrons • Cytochromes have a Fe2+to act as the electron acceptor/donor • Complex IV is the irreversible binding site of cyanide and is inhibited by CO too • Complex II contains the enzyme succinate dehydrogenase (step 6 of the Krebs cycle) and uses FADH2 • After Complex IV, the electrons are passed on to O with two H+ to produce H2O

  12. Chemiosmosis and ATP Synthase • Proton-motive Force electrochemical gradient of protons used to power ATP synthase • H+ fall down gradient through chemiosmosis and cause a conformational change in ATP synthase that forces ADP and Pi to bind together • 1 NADH 2.5 ATP • 1 FADH21.5 ATP • Total the ATP: • Glycolysis= 2 ATP • Krebs Cycle= 2 ATP • Oxidative Phosphorylation= 28 ATP Total = 32 ATP

  13. Energy Efficiency • Some cells only produce 30 ATP • Less efficient electron transporter (FADH) is used in glycolysis • Found in brain tissue and skeletal muscles • What type of tissue use the more efficient 32 ATP system? • Constantly active organs like the heart, liver and kidneys • How do muscles compensate their ATP needs since they have a less efficient system? • Lactic acid Fermentation • ATP 7 kcal/mol • Glucose 686 kcal/mol • How efficient is this whole process? • 33% ((7x322)/686)x100 FADHFADH

  14. Aerobic and Anaerobic Reactions • Organism can be: • Strict anaerobes can’t survive in oxygen • Strict aerobes can’t survive without oxygen • Facultative aerobes can survive with or without oxygen • What parts of cellular respiration are aerobic/anaerobic? • Aerobic Krebs cycle/Oxidative Phosphorylation • Anaerobic Glycolysis • Anaerobic Organism can still do glycolysis, but what is left at the end? • pyruvate • Breaking down pyruvate after glycolysis creates different kinds of fermentation

  15. Fermentation • Alcoholic pyruvate is converted into ethanol (alcohol and fuel) and released from the cell • Also releases CO2; used to make bread/cakes raise • Lactic Acid pyruvate is converted into lactate • Used to flavor yogurt • Energy supply in muscles when oxygen runs low • Why is it dangerous to us? • Builds up in cells and lowers pH (acidic) • Causes muscle crams and soreness after working out • Must be removed from the cells and broken down in the liver

  16. Homework • Read Ch. 9 and do Ch. 9 vocab • Ch. 8 vocab due Tuesday • Ch 8. “Test Your Knowledge” and “Interpret the Data” p.175 for Tuesday • Ch. 7 “Test Your Knowledge” on p. 153-154 and “Design the Experiment” on p. 154 due Tuesday • Test on Ch. 6, 7, and 8 on Wednesday • Lab on photosynthesis on Wednesday • Ch. 9, 10 and 11 still to cover!

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