Lecture Notes on Cellular Respiration and Fermentation by Dr. D

Introduction

• Presenter: Dr. D
• Topics Covered: Cellular respiration and fermentation
• Approach: Story-like explanation to simplify complex biology processes

Cellular Respiration

• Purpose: Production of ATP in mitochondria (Powerhouse of the cell)
• Equation of Cellular Respiration:
  • Reactants: Glucose (C6H12O6) and Oxygen (O2)
  • Products: Carbon Dioxide (CO2), Water (H2O), and ATP (30-32 ATP)

Mitochondrial Structure

• Components:
  • Outer Membrane
  • Inner Membrane
  • Intermembrane Space
  • Matrix

ATP Synthase

• Function: Combines ADP and inorganic phosphate (Pi) to form ATP
• Structure: Transmembrane protein with a spinning top portion
• Mechanism: Proton flow drives spinning to synthesize ATP
• Output: Produces 28 of the 30-32 ATP molecules per glucose

Proton Motive Force and Chemiosmosis

• Protons (H+): High concentration in the intermembrane space
• Chemiosmosis: Diffusion of protons across a membrane
• Proton Motive Force (PMF): Drives ATP Synthase activity

Electron Transport Chain (ETC)

• Complexes: 1, 2, 3, 4
• Function: Electron transfer through complexes drives proton pumping
• Final Electron Acceptor: Oxygen, forming water

Glycolysis

• Location: Cytoplasm
• Process:
  • Breakdown of glucose into two pyruvate molecules
  • Net gain of 2 ATP (via substrate-level phosphorylation) and 2 NADH

Pyruvate Oxidation

• Function: Conversion of pyruvate to Acetyl-CoA
• Outputs: 2 NADH, 2 CO2, 2 Acetyl-CoA

Citric Acid Cycle (Krebs Cycle)

• Location: Mitochondrial matrix
• Process:
  • Completes glucose oxidation
  • Produces 6 NADH, 2 FADH2, 4 CO2, 2 ATP (substrate-level phosphorylation)

Oxidative Phosphorylation

• Components: Electron Transport Chain and ATP Synthase
• Function: Produces the majority of ATP (28 ATP)

Comparison in Eukaryotes vs. Prokaryotes

• Eukaryotes: Net 30 ATP
• Prokaryotes: Net 32 ATP (No mitochondria, no transport cost)

Fermentation

• Types: Lactic Acid Fermentation (Animals) and Alcohol Fermentation (Yeast)
• Lactic Acid Fermentation:
  • Occurs: Lack of oxygen
  • Process: Pyruvate reduced to lactic acid to regenerate NAD+
• Alcohol Fermentation:
  • Occurs: Yeast in anaerobic conditions
  • Process: Pyruvate converted to ethanol and CO2

Key Concepts

• Aerobic Respiration: Oxygen is the terminal electron acceptor
• Anaerobic Respiration: Non-oxygen terminal electron acceptors (not in humans)
• Fermentation:
  • Only glycolysis proceeds, producing 2 ATP
  • Necessary under low oxygen conditions to regenerate NAD+

Application

• Importance in understanding breathing, weight loss, exercise, and fermentation in food production

Conclusion

• Importance: Cellular respiration is vital for life, explaining essential biological processes and applications in medicine and nutrition.