Glycolysis and Krebs Cycle

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Glycolysis and Krebs Cycle
2013-11-21 02:19:57
Glycolysis Krebs

These notes include questions on the glycolysis cycle and the Krebs cycle. As well as some information of Energy metabolism and oxidative phosphorylation.
Show Answers:

  1. What are exergonic reactions?
    Give off free energy
  2. What are endergonic reactions?
    Require energy to be added. This energy does from high energy bonds (can end up with more free energy)
  3. when do exergonic and endergonic reactions occur?
    Often together, they're coupled.
  4. What are sources of energy?
    Macro-nutrients (carbs, protein, and fats)
  5. What is the distinction of Carbs?
    • Monosaccharides (Glucose, fructose)
    • Disaccharides (Sucrose--> glucose + fructose), maltose --> (glucose +glucose)
    • Polysaccharides (either plant or animal source, glycogen most common in animal)
  6. What's important about fats?
    One gram=9.4 kcal

    insoluble in water
  7. What are the four groups of fats?
    • - Fatty Acids (stored form of triglycerides)
    • - Triglycerids =3 fatty acids and glycerol (from liver)
    • -Phospholipids (structure, insulation of nerves)
    • - Steroids (cholesterol- structure and hormones; estrogen)
  8. What is the importance of protein?
    • One gram= 5.6 kcal (in 70 kg person)
    • Composed of 20 different amino acids
    • 9 essential amino acids
    • Must be broken down into their respective AA before being used for energy
  9. What does ATP consist of?
    Adenosine, ribose and phosphates
  10. What might Adenosine, ribose and phosphates form?
    From What?

    ADP or AMP
  11. The breakage of _____ by _____ yields energy
    the phosphate bond

  12. Cells use _____ reactions (breakdown of foods) to form ___ via _______ reactions



    (ATP is then used again)
  13. What is the purpose of glycolysis?
    • production of ATP without Oxygen
    • (enzymatically catalyzed coupled reactions)
  14. What are the two phases of glycolysis?
    Energy investment

    Energy generated
  15. How much ATP does investment stage of glycolysis create?
    2 ATP
  16. How much ATP does generated stage of glycolysis create?
    4 ATP
  17. Describe steps of glycolysis.
    Glucose (C6) uses ATP and creates ADP --> glucose-6-phosphate (C6) -->Fructose-6- phosphate (C6) uses another ATP to create ADP--> Fructose 1,6-diphosphate (C6) This molecule splits into two identical molecules!!! --> Glyceraldehyde-3-phosphate and Dihydroxyacetone phosphate (C3) use NAD+ and convert to NADH--> 1,3 diphosphoglycerate (C3) uses ADP to make ATP --> 3-phosphoglycerate (C3) --> 2 phosphoenolypyruvate (C3) produces water -->Phosphoenolypyruvate (C3) uses ADP to create another ATP -->Pyruvate (C3). Since two of these processes occur 4 ATP made, but 2 used in beginning so net is 2 ATP.
  18. What happens if Oxygen is not available for glycolysis?
    Lactic acid will be produced instead of pyruvate.
  19. What are the entering substrates of glycolysis?
    Glucose and other mono-saccharides
  20. What is the enzyme locations of glycolysis?
    Cytosol (liquide/aqueous part of cytoplasm)
  21. What is the net ATP production of glycolysis?
    2 ATP formed directly per molecule of glucose entering pathway can be produced in the absence of oxygen (anaerobically).
  22. What is the coenzyme production of glycolysis?
    2 NADH= 2 H+ formed under aerobic conditions
  23. What are the final products of glycolysis?
    Pyruvate (aerobic)

    Lactate (anaerobic)
  24. What is the net reaction of glycolysis under aerobic conditions?
    Glucose + 2ADP + 2 Pi + 2NAD+ -->(yeilds 2 ATP) 2 pyruvate + 2ATP +2NADH +2H+ + 2 H2O
  25. What is the net reaction of glycolysis under anaerobic conditions?
    Glucose +2ADP + 2 Pi --> (gives total of 3 ATP) 2 lactate + 2 ATP + 2 H2O
  26. What is the fate of pyruvate after glycolysis?
    Under anaerobic conditions it will be converted into 2 lactate, or 2 Ethanol + CO2 (alcohol fermentation yeast)

    Aerobic conditions= creates CO2 and is turned into 2 Acetyl-CoA and then used in Krebs
  27. Can Krebs work in both Aerobic and Anaerobic conditions?
    No! Only Aerobic, it needs oxygen!
  28. What are the steps of the Krebs Cycle?
    Pyruvate uses NAD to make NADH + H+, and produces CO2--> Acetyl Coenzyme A (C2) combines with oxaloacetate and H2O is added and CoA is removed-->Citrate (C6)-->Isocitrate (C6) loses CO2 and H+and uses NAD to create NADH + H+--> Alpha ketoglutarate (C5) loses CO2 and H, gains H2O, uses CoA and makes another NADH + H+-->Succinyl coenzyme A (C4) uses GDP to produce GTP and essentially ATP, and CoA --> Succinate (C4) loses 2 more H+ and forms FADH + H+-->Fumarate (C4) gains water --> Malate (C4) loses 2 H+, uses NAD to make NADH + H+ -->Oxaloacetate (C4) and then it joins with water and Acetyl Coenzyme A and the cycle restarts.
  29. How many ATP does FADH2 yield?
  30. How many ATP is one GTP?
  31. What are the entering substrates of the Krebs cycle?
    Acetyl coenzyme A- acetyl group from pyruvate, fatty acids and amino acids
  32. What is the enzyme location of TCA cycle?
    Inner compartment of mitochondria (matrix)
  33. What is the ATP production from the TCA cycle?
    • - 1 GTP formed directly which can be converted into one ATP
    • - operates only under aerobic conditions, even hough molecular oxygen is not used directly in this pathway
  34. What is the coenzyme production of the TCA cycle
    (3 NADH + 3 H+ and 2 FADH2) X2
  35. What are the final products of the citric acid cycle?
    • - 2 CO2 for each molecule of acetyl coenzyme A entering pathway
    • - intermediates used to synthesize amino acids and other organic molecules required for each cell
  36. What is the net reaction of the citric acid cycle?
    Acetyl CoA + 3 NAD + FAD +GDP + Pi + 2 H2O --> 2 CO2 + CoA + 3NADH + 3 H+ +FADH2 + GTP
  37. What does oxidative phosphorylation involve?
    The transfer of electrons from a substrate through a series of carriers and the capture of energy in ATP at certain transfer.
  38. What ultimately happens to the electrons and hydrogen in Oxidative Phophorylation
    ions combine with oxygen to form water
  39. During each transfer of electrons in Oxidative Phophorylation, one substance is ______ and the other is ____


    REDOX reaction
  40. In order for the electron transport to occur, what needs to be present?
  41. Where are the enzymes that catalyze the electron transfer located?
    On the cristae of the mitochondria, adjacent to those in the matrix and catalyze krebs cycle reactions
  42. What does each reaction require in Oxidative Phophorylation
    a specific enzyme and most also require a coenzyme.
  43. What are the entering substrates of Oxidative Phophorylation?
    Hydrogen atoms that were created from glycolysis and Krebs

    and molecular oxygen
  44. Where are the enzymes for Oxidative Phophorylation located?
    inner mitochondrial membrane
  45. What is the ATP production of Oxidative Phophorylation?
    • - 2-3 ATP formed from each NADP + H+
    • - 1-2 ATP formed from each FADH2
  46. What are the final products of Oxidative Phophorylation?
    H2O- one molecule for each pair of hydrogen entering pathway
  47. Net reaction of Oxidative Phophorylation
    1/2 O2 + NADH + H+ + 3 ADP + 3 Pi --> H2O + NAD + 3 ATP
  48. How many total ATP are created from Aerobic oxidation of glucose?
  49. What is the respiratory quotient?
    RQ= (volume of CO2 produced)/ (Volume of O2 used)

    RQ= 6/6=1
  50. What is the summary reaction of the oxidation of glucose?
    C6H12O6 + 6O2+ (34-36) ADP + (34-36) Pi--> 6CO2 + 6 H2O + 34-36 ATP

    Use highlighted in RQ
  51. What is the RQ in a mixed diet?
    • 0.8
    • 1.0
    • 0.8
    • 0.7