Cellular Respiration Lecture Notes

Introduction

• Most people can hold breath for 30-45 seconds.
• 3-4 minutes without oxygen may cause brain damage or death.
• Rule of Three:
  • 3 weeks without food
  • 3 days without water
  • 3 minutes without oxygen
• Oxygen is crucial for cellular respiration.
• Topics to cover: cellular respiration process, aerobic respiration.

Cellular Respiration Overview

• Goal: Use glucose and oxygen to generate ATP, water, carbon dioxide, and heat.
• ATP: Universal cellular energy currency.
• Types of respiration:
  • Aerobic Respiration: Requires oxygen, yields more energy.
  • Anaerobic Respiration: Little/no oxygen, yields less energy.

Eukaryotic Respiration

• Occurs in cytoplasm and mitochondria.
• Mitochondrial compartments:
  • Intermembrane space (outer)
  • Matrix (inner)

Stages of Aerobic Respiration

1. Glycolysis

   • Occurs in cytoplasm.
   • Breaks down glucose into pyruvate.
   • Invests 2 ATP, produces 4 ATP (net gain: 2 ATP).
   • Produces NADH (electron carrier).

2. Prep Steps

   • Modifies pyruvate using coenzyme A.
   • Produces acetyl CoA, CO2, and NADH.

3. Krebs Cycle (Citric Acid Cycle)

   • Occurs in the mitochondrial matrix.
   • Generates ATP, NADH, FADH2, CO2.
   • Acetyl CoA combines with oxaloacetate.
   • Produces waste CO2.

4. Electron Transport Chain (ETC) & Chemiosmosis

   • Occurs across mitochondrial membrane.
   • ETC uses NADH and FADH2 to create proton gradient.
   • Oxygen is final electron acceptor, forming water.
   • Chemiosmosis: ATP synthase uses proton flow to generate ATP.

Additional Concepts

• NADH & FADH2: Mobile electron carriers.
• Oxidation & Reduction:
  • OIL RIG mnemonic: Oxidation is Losing, Reduction is Gaining.
• ATP Synthase & Proton Gradient: Essential for ATP production.

Summary of ATP Production

• Glycolysis: 2 ATP (net), 2 NADH
• Prep Steps: 0 ATP, 2 NADH
• Krebs Cycle (per glucose): 2 ATP, 6 NADH, 2 FADH2
• ETC yields ~34 ATP from NADH & FADH2

Conclusion

• Cellular respiration converts glucose and oxygen into ATP, CO2, and water.
• Importance of oxygen and consequences of its absence (e.g., suffocation).