Lecture on Electron Transport Chain and Oxidative Phosphorylation
Overview
- Previous stages: Glycolysis, Intermediate Step, Krebs Cycle
- Total energy generated so far: 4 ATP
- 2 ATP from Glycolysis
- 2 ATP from Krebs Cycle
- Initial ATP usage: 2 ATP to transport building blocks into the mitochondria
Key Concepts
Electron Carriers
- NADH and FADH2 are electron carriers
- "Casino chips" analogy: Loaded with electrons and hydrogen ions, ready to "cash in"
Electron Transport Chain (ETC)
- Function: Transfer electrons via a series of complexes
- Proton Movement: Key to ATP production
- Movement of protons (H⁺ ions) generates energy
- H⁺ ions = Hydrogen ions = Protons
Oxidative Phosphorylation
- Different from substrate-level phosphorylation (occurs without oxygen)
- Uses oxygen, making it "oxidative"
Detailed Process
Role of NADH and FADH2
- NADH: Generates energy for 3 ATP
- FADH2: Generates energy for 2 ATP
Step-by-step Electron Transfer
- Electrons transferred stepwise, releasing energy at each step
- Energy used to pump H⁺ ions across the mitochondrial membrane
- Proton Pumps: Transport H⁺ ions using energy from electrons
Importance of Oxygen
- Final electron acceptor: Oxygen
- Oxygen accepts used electrons and forms water
- Essential for aerobic respiration
- Without oxygen, ETC stops, halting ATP production
Concentration Gradient
- High concentration of H⁺ ions outside the mitochondrial membrane
- Creates an electrochemical gradient
- Diffusion: H⁺ ions want to move back inside
ATP Synthase
- Function: Allows H⁺ ions back into the mitochondria
- Acts as a turbine, spinning as H⁺ ions flow through
- ATP Production: Energy from spinning adds phosphate to ADP, forming ATP
Chemiosmosis
- Term for the flow of H⁺ ions through ATP synthase
Clinical Relevance
- Cyanide Poisoning: Blocks cytochrome c, stopping ETC
- Result: Quick death due to halted ATP production
Summary
- Entire process from glucose to ATP involves multiple steps
- Human yield: 36 ATP
- Bacteria yield: 38 ATP
- Continuous process requiring constant electron supply
Conclusion
- Understanding requires time and review
- Encouragement to study and revisit material for better grasp
Note: This process is complex and requires multiple reviews to fully understand. Keep studying and revisiting this material.