⚡️ 7. Summary of ATP Formation during Glucose Breakdown

• What is the total number of ATP molecules formed from one glucose molecule under optimal conditions?

  38 ATP molecules
• How many ATP molecules are formed during glycolysis?

  Four ATP molecules
• What is the net gain of ATP from glycolysis after accounting for the two ATP expended?

  Two ATP molecules
• How many revolutions of the citric acid cycle occur for each glucose molecule?

  Two revolutions
• How many ATP molecules are produced during each revolution of the citric acid cycle?

  One ATP molecule
• How many hydrogen atoms are released during the breakdown of glucose?

  24 hydrogen atoms
• How many ATP molecules are produced from the oxidation of hydrogen atoms during the chemiosmotic mechanism?

  30 ATP molecules
• How many additional ATP molecules are produced from the remaining four hydrogen atoms?

  Four ATP molecules
• What is the total energy stored in ATP from one glucose molecule?

  456,000 calories
• What percentage of energy from glucose is transferred to ATP?

  66 percent
• What happens to the remaining 34 percent of energy from glucose?

  It becomes heat
• How does ATP control glycolysis and glucose oxidation?

  By inhibiting phosphofructokinase enzyme
• What effect does excess ATP have on phosphofructokinase?

  It slows or stops glycolysis
• What role does ADP play in glycolysis?

  It increases phosphofructokinase activity
• What happens when ATP is used by tissues?

  ADP and AMP levels increase
• What is the effect of citrate ion on phosphofructokinase?

  It inhibits the enzyme
• What happens if all ADP is converted into ATP?

  No additional ATP can be formed
• What is anaerobic glycolysis?

  Energy release without oxygen
• How much energy is released during anaerobic glycolysis?

  24,000 calories
• What percentage of total energy in glucose is used to form ATP during anaerobic glycolysis?

  About 3 percent
• Why is anaerobic energy considered wasteful?

  It uses glucose inefficiently
• What are the main steps in ATP formation during glucose breakdown?

  1. Glycolysis: 4 ATP formed, 2 expended (net gain: 2 ATP)
  2. Citric acid cycle: 2 ATP from 2 revolutions
  3. Chemiosmotic mechanism: 30 ATP from hydrogen oxidation
  4. Additional 4 ATP from remaining hydrogen atoms
  5. Total: 38 ATP from one glucose molecule
• What are the feedback mechanisms controlling glycolysis and glucose oxidation?

  • ATP inhibits phosphofructokinase
  • ADP increases phosphofructokinase activity
  • Citrate ion inhibits phosphofructokinase
  • ADP and AMP reactivate energy processes when ATP is low
• What are the consequences of anaerobic glycolysis?

  • Energy release without oxygen
  • Only 24,000 calories of energy produced
  • Represents about 3% of glucose energy
  • Can be lifesaving for a few minutes
• What is formed during anaerobic glycolysis?

  Lactic acid
• What does the law of mass action state?

  Reaction rate decreases as products build up
• What are the two end products of glycolytic reactions?

  Pyruvic acid and NADH
• What happens when the end products of glycolysis build up?

  Glycolytic process stops and ATP formation halts
• How does lactic acid allow glycolysis to continue?

  Lactic acid acts as a sinkhole for end products
• What is the significance of lactic acid during anaerobic conditions?

  It allows glycolysis to supply ATP for longer
• How long can glycolysis proceed without lactic acid conversion?

  A few seconds
• What happens to lactic acid when oxygen becomes available again?

  It is reconverted to pyruvic acid and NADH
• What occurs to pyruvic acid after lactic acid reconversion?

  It is oxidized to form ATP
• What percentage of excess pyruvic acid is converted back into glucose?

  Three fourths
• Where does most reconversion of lactic acid occur?

  In the liver
• How does the heart use lactic acid?

  It converts lactic acid to pyruvic acid for energy
• When does the heart primarily use lactic acid for energy?

  During heavy exercise
• What is the process of lactic acid formation during anaerobic glycolysis?

  • Pyruvic acid and NADH build up
  • Reaction rate decreases due to mass action
  • Pyruvic acid converts to lactic acid
  • Lactic acid diffuses into extracellular fluids
  • Allows glycolysis to continue for longer
• What happens to lactic acid when oxygen is reintroduced?

  • Lactic acid reconverted to pyruvic acid
  • NADH is produced
  • Pyruvic acid is oxidized to generate ATP
  • Excess pyruvic acid can convert to glucose
• How does the heart utilize lactic acid during exercise?

  • Converts lactic acid to pyruvic acid
  • Uses pyruvic acid for energy
  • Occurs when lactic acid is released from muscles