Cellular Respiration

  1. Two main pathways of cellular respiration
    • Aerobic Respiration
    • Anaerobic Respiration (fermentation- which is different from anaerobic)
  2. What is the energy harvested during respiration used for?
    To regenerate ATP
  3. Cellular respiration can be described as:
    • Exergonic
    • Catabolic- you're breaking stuff down
    • deltaG<0- products will have lower free energy than reactants
  4. Why is energy harvested in a stepwise manner
    If glucose was oxidized all at once, too much energy would be lost
  5. How are hydrogen atoms transferred to oxygen?
    • They are passed to an electron carrier.
    • NAD+ is the main electron carrier and is essentially a shuttle (NADH reduced)
  6. Stages of Cellular Respiration
    • Glycolysis
    • Pyruvate Processing
    • Citric Acid Cycle
    • ETC & Oxidative phosphorylation
  7. Reactants and Products of Glycolysis
    • Glucose + 2 ATP + NAD+ --->
    • 2 Pyruvate + 4 ATP (2 Net ATP) + 2 NADH
  8. Reactants and Products of Pyruvate Processing
    • Pyruvate + Coenzyme A + NAD+-->
    • Acetyl CoA + CO2 + NADH
  9. Reactants and Products of Citric Acid Cycle
    • Acetyl CoA + H2O + 3 NAD+ + FAD ->
    • 2 CO2 + H2O + 3 NADH + FADH+ GTP (ATP)
  10. Reactants and products of ETC & Oxidative Phosphorylation
    • NADH + FADH2 + 1/2 O2 + ADP + Pi ->
    • ATP + H2O + NAD+ + FAD
  11. Where does glycolysis take place?
  12. What does glycolysis do?
    • Splits glucose into 2 molecules of pyruvate
    • Requires 2 ATP but gives off 4 ATP (net yield of 2 ATP)
  13. What happens to the pyruvate after glycolysis?
    It is shuttled into the mitochondria
  14. Initial input/Product of glycolysis
    • Glucose
    • 2 Pyruvate
  15. Outputs from glycolysis process
    • ADP
    • ATP
    • NADH
    • H2O
  16. Inputs from glycolysis process
    • ATP
    • NAD+
  17. What is the net yield of ATP from glycolysis
    Gain 2 ATP
  18. Net yield of NADH
    Gain of 2 NADH
  19. 3 steps in Pyruvate Processing
    • Using a transport protein:
    • The carboxyl group is removed to give off CO2
    • The remaining 2-carbon is oxidized and the electrons lost is used to turn NAD+ into NADH
    • Coenzyme A is added to form acetyl CoA (which has high potential energy
  20. Inputs of pyruvate processing
    • 2 pyruvate
    • 2 coenzyme A
    • 2 NAD+
  21. Outputs of pyruvate processing
    • 2 Acetyl CoA
    • 2 NADH
    • 2 CO2
  22. Net yield of NADH in pyruvate processing
    Gain of 2 NADH
  23. Where does the Krebs Cycle (Citric Acid Cycle) occur?
    Mitochondrial matrix
  24. What does one Citric Acid produce?
    • 2 CO2
    • 1 ATP (GTP)
    • 3 NADH
    • 1 FADH2
    • CoA and oxaloacetate are recycled
  25. Where is most of the energy from glucose in cellular respiration?
    • Most of energy extracted from glucose is tied up in NADH and FADH2
    • It is in the electron carriers
  26. A molecule that is phosphorylated...
    has increased chemical potential energy; it is primed to do cellular work
  27. During glycolysis for each mole of glucose oxidized to pyruvate:
    2 moles of ATP are used and 4 moles of ATP are produced
  28. Oxidative Phosphorylation
    • Generates ATP by adding P to ADP
    • This is where the majority of ATP is produced
    • Two steps:
    • -Electron Transport Chain
    • -Chemiosmosis
  29. Electron Transport Chain
    • Collection of molecules embedded in the mitochondrial inner membrane
    • Electrons are dropped off by NADH and FADH2
    • Still not ATP Production from this
  30. How does the electron transport chain work?
    Electron carriers alternate between reduced and oxidized states as they accept and donate e-
  31. What is the final electron acceptor in the electron transport chain?
    Oxygen which also picks up 2 H+ ions to form H2O
  32. Which pathways generate reduced electron carriers?
    • Citric Acid cycle
    • Glycolysis
    • Pyruvate Oxidation
  33. Chemiosmosis
    • Diffusion of ions (H+) down their electrochemical gradient to generate ATP
    • Exergonic flow of electrons is used to pump H+ across the membrane (into the intermembrane space)
    • -generates a gradient= proton motive force
  34. What does the chemiosmotic synthesis of ATP require?
    The electron transport in the inner mitochondrial membrane be couple to proton transport across the same membrane
  35. ATP Synthase
    • Uses energy of the H+ gradient to power ATP synthesis
    • -Located in the mitochondrial inner membrane
  36. How does ATP Synthase work?
    • H+ ions flow through ATP synthase down their concentration gradient
    • -bind to active sites and cause conformational change= rotor spins
    • -this activates catalytic sites that generate ATP
  37. During aerobic respiration, electrons travel downhill in which sequence?
    Food -> NADH -> Electron Transport Chain -> Oxygen
  38. What is the actual yield of ATP after cellular respiration?
    What is the theoretical yield?
    • 29
    • 38
  39. In cellular respiration, the energy for most ATP synthesis is supplied by?
    A proton gradient across a membrane
  40. What percentage of potential energy of glucose is transferred to ATP?
    • 31%
    • The rest is given off as heat
  41. Why are carbohydrates and fats considered high energy foods?
    They have a lot of electrons associated with hydrogen
  42. Hibernation
    • Animals can reduce the efficiency of respiration
    • Brown fat contains cells full of mitochondria
    • -the inner membrane contains an uncoupling protein which allows H+ to flow back down their concentration gradient without generating ATP
    • -This allows the oxidation of stored fuel to generate heat without buildup of ATP
  43. What would happen if animals couldn't hibernation?
    ATP would accumulate (since the animal's metabolism is low) and respiration would be shut down due to control mechanisms
  44. Drugs known as uncouplers facilitate diffusion of protons across the membrane when such a drug is added, what happens to ATP synthesis & oxygen consumption, if the rates of glycolysis and citric acid cycle same?
    ATP synthesis will decrease, oxygen consumption stays the same
  45. Anaerobic Respiration
    • Still uses an electron transport chain but oxygen is not the final electron acceptor
    • Other substances can include Iron, Sulfate ion, or carbon dioxide
    • Can also use different electron donors.
    • -glucose doesn't have to be the starting material
  46. Fermentation
    Process to generate energy without using oxygen or an electron transport chain
  47. What does fermentation use to allow glycolysis to continue if no oxygen is present?
    • Metabolic pathway to regenerate NAD+
    • (you need NAD+ to pick up electrons, so glycolysis can keep running)
  48. What happens in alcohol fermentation
    • Pyruvate is reduced to ethanol
    • NADH is going to be oxidized to be NAD+
  49. What is alcohol fermentation used for?
    Used by some bacteria and yeast to make beer, wine, liquor, and bread.
  50. What happens in lactic acid fermentation?
    Pyruvate is reduced directly by NADH to form lactate
  51. Why do muscles use lactic acid fermentation?
    Muscle cells use this process when supply of oxygen can't keep up with energy demand
  52. What is happening when you are deprived of oxygen?
    • Lack of ATP production
    • No oxygen means nothing to pick up electrons at the electron transport chain and electrons back up
  53. Why can't your cells just switch over to fermentation?
    It doesn't produce enough ATP to sustain your energy requirement for your body
  54. A gram of fat produces 2x the ATP generated from 1 g of carbohydrate. Why?
    Why does this make it hard to lose weight?
    • There are more hydrogens in fat
    • Since fat produces 2x ATP, you have to work out twice as hard to burn it.
  55. Biosynthesis
    • Simple compounds are modified, converted into other compounds, or joined together to form macromolecules.
    • It is anabolic because it requires energy
  56. How is cellular respiration regulated?
    • Follows principles of supply and demand
    • Prevents cell from wasting energy making something it already has
    • The main mechanism of control is feedback inhibition
  57. What is the probably effect on ATP production of a low-calorie diet?
    ATP production would remain constant as stored fats or other body molecules are oxidized
  58. You have a friend who lost 7 kg (15 lbs) of fat on a regimen of strict diet and exercise. How did the fat leave her body?
    It was released as CO2 and water
Card Set
Cellular Respiration