Krebs Cycle Lecture Notes

Overview

• Purpose: Breakdown of acetyl-CoA to carbon dioxide, completing the oxidation of glucose.
• Location: Mitochondrial matrix.
• Significance: Produces electron carriers (NADH and FADH2) and ATP.

Initial Reaction

• Acetyl-CoA combines with oxaloacetate (4-carbon molecule)
  • Forms citric acid (6-carbon molecule)
• Alternative Name: Citric Acid Cycle

Oxidation and Decarboxylation

1. Citric Acid Oxidation
   • Electrons transferred to NAD+ forming NADH
   • Release of CO2
   • Results in a 5-carbon molecule
2. Further Oxidation
   • Produces another NADH
   • Release of another CO2
   • Results in a 4-carbon molecule

ATP Production

• 4-carbon molecule is transformed
• Energy released joins ADP and phosphate to form ATP

FADH2 Formation

• 4-carbon molecule is further oxidized
• Electrons transferred to FAD forming FADH2

Final Oxidation

• Final 4-carbon molecule oxidation
• Formation of additional NADH
• Regenerates oxaloacetate, completing the cycle

Importance

• Electron Carriers: NADH and FADH2 carry electrons to the electron transport chain
• ATP: Direct energy currency for the cell
• CO2: Released as a waste product, exhaled from the body

Additional Resources

• Suggested activity: Respiration interactive activity at BioMan Biology
• Explore other educational tools: games, quizzes, and learning experiences at BioMan Biology