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Cellular Respiration

Cellular Respiration. Harvesting Chemical Energy. So we see how energy enters food chains (via autotrophs) we can look at how organisms use that energy to fuel their bodies. Plants and animals both use products of photosynthesis (glucose) for metabolic fuel

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Cellular Respiration

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  1. Cellular Respiration

  2. Harvesting Chemical Energy • So we see how energy enters food chains (via autotrophs) we can look at how organisms use that energy to fuel their bodies. • Plants and animals both use products of photosynthesis (glucose) for metabolic fuel • Heterotrophs: must take in energy from outside sources, cannot make their own e.g. animals • When we take in glucose (or other carbs), proteins, and fats-these foods don’t come to us the way our cells can use them

  3. When we take in glucose (or other carbs), proteins, and fats-these foods don’t come to us the way our cells can use them • Animals use cellular respiration to transformchemical energy in food into chemical energy cells can use: ATP • These reactions proceed the same way in plants and animals. • Overall Reaction: • C6H12O6 + 6O2→ 6CO2 + 6H2O

  4. How much energy is actually present in food? • 1 g of sugar glucose (C6H12O6) when burned in the presence of O2 releases 3811 calories of heat energy

  5. How many calories do you burn a day?

  6. How many calories do you burn a day? • Male • 150 lb • 5’9” • Somewhat active • Burns 3023 kcal a day or 3023 Calories or 3,023,000 calories • 1 g of glucose produces 3811 calories

  7. Calorie • calorie: The amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius • Calorie: food labels • 1000 calories • Cells don’t burn glucose – cells gradually release energy from glucose and other food compounds • Cells release energy from glucose by performing cellular respiration

  8. Cellular Respiration Overview • Breakdown of glucose begins in the cytoplasm: the liquid matrix inside the cell • At this point life diverges into two forms and two pathways • Anaerobic cellular respiration (aka fermentation) • Aerobic cellular respiration

  9. Cellular Respiration • Cellular respiration is the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen • C6H12O6 + 6O2→ 6CO2 + 6H2O

  10. Cellular Respiration • Glycolysis • The Krebs Cycle • Electron Transport

  11. Glycolysis • The process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid

  12. http://upload.wikimedia.org/wikipedia/commons/1/17/Glycolysis2.svghttp://upload.wikimedia.org/wikipedia/commons/1/17/Glycolysis2.svg

  13. Glycolysis – ATP Production • 2 ATP used • 4 ATP produced • Net gain of 2 ATP

  14. Glycolysis – NADH Production • NAD+ accepts a pair of high-energy electrons until they are transferred to other molecules

  15. Anaerobic Respiration • When oxygen is not present, glycolysis is followed by a different pathway – FERMENTATION • Alcoholic fermentation (yeast) • Pyruvic acid + NADH  alcohol + CO2 + NAD+ • Causes bread to rise – CO2 forms the air spaces that you see in bread • Lactic acid fermentation (muscles) • Pyruvic acid + NADH  lactic acid + NAD+

  16. Substrate Level Phosphorylation

  17. Glycolysis

  18. Krebs Cycle

  19. Citric Acid Production • Pyruvic acid enters the mitochondrion • A carbon is removed, forming CO2 • Electrons are removed: NAD+  NADH • Coenzyme A joins the 2-carbon molecule, forming Acetyl-Co-A • Acetyl-Co-A then adds the 2-carbon acetyl group to a 4-carbon compound (oxaloacetate), forming Citric Acid

  20. Cytoplasm Inner Mitochondrial Space Krebs Cycle

  21. Acetyl Co A  Citric Acid

  22. Energy Extraction • Citric acid is broken down into a 5-carbon compound, then into a 4 carbon compound • Produces • 2 more molecules of CO2 • NAD+  NADH • FAD+  FADH2 • 1 ATP

  23. Electron Transport • Electrons from NADH and FADH2 are used in the electron transport chain to convert ADP to ATP

  24. Electron Transport Chain • Composed of carrier proteins located in the inner membrane of the mitochondrion • High-energy electrons are passed from one carrier protein to the next • An enzyme combines these electrons with hydrogen ions and oxygen  H2O • Oxygen is the final electron acceptor of the electron transport chain • Oxygen is essential for getting rid of low-energy electrons and hydrogen ions • Low-energy electron and hydrogen ions are waste products of cellular respiration

  25. Hydrogen Ion Movement • Every time 2 high-energy electrons transport down the electron transport chain, their energy is used to transport hydrogen ions (H+) across the membrane • H+ build up in the intermembrane space, making it positively charged • The other side of the membrane is negatively charge

  26. ATP Production • The cell uses the build up of charge differences • As H+ escape through the ion channels, the ATP synthase (a protein enzyme) spins • Each time the ATP synthase spins, the enzyme grabs an ADP and attaches a phosphate, forming ATP • Each pair of high-energy electrons that moves down the electron transport chain provides enough energy to produce three molecules of ATP

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