Lecture Notes: Aerobic Cellular Respiration in Eukaryotic Cells

Introduction

• Discussion on morning energy levels compared to constant cell activity.
• ATP (Adenosine Triphosphate):
  • Energy currency of the cell.
  • A type of nucleic acid with three phosphates.
  • Essential for active transport and cell survival.

ATP Production

• ATP must be produced by all cells (prokaryotic and eukaryotic).
• Aerobic Cellular Respiration:
  • Focus on eukaryotic cells with membrane-bound organelles (nucleus, mitochondria).
  • Eukaryotic cells include protists, fungi, animals, and plants.

The Aerobic Cellular Respiration Process

• Equation Overview:
  • Inputs (reactants) on the left; outputs (products) on the right.
  • Similar to but not opposite of photosynthesis.
  • Cells break down glucose to make ATP.

Steps of Aerobic Cellular Respiration

Step 1: Glycolysis

• Occurs in the cytoplasm.
• Anaerobic process (does not require oxygen).
• Converts glucose into pyruvate. Uses some ATP to start with a net yield of:
  • 2 Pyruvate
  • 2 ATP
  • 2 NADH
• NADH: A coenzyme that transfers electrons.

Intermediate Step

• Pyruvate transported to the mitochondrial matrix.
• Converted to acetyl CoA, releasing carbon dioxide and producing 2 NADH.

Step 2: Krebs Cycle (Citric Acid Cycle)

• Occurs in the mitochondrial matrix.
• Aerobic (needs oxygen indirectly).
• Produces:
  • 2 ATP
  • 6 NADH
  • 2 FADH2 (another electron-transferring coenzyme).

Step 3: Electron Transport Chain and Chemiosmosis

• Occurs in the inner mitochondrial membrane.
• Requires oxygen (aerobic step).
• Electrons transferred from NADH/FADH2 to proteins and carriers.
• Creates a proton gradient, leading to ATP production.
• Oxygen accepts electrons forming water (H2O).

ATP Yield

• Variable estimates for ATP production:
  • 26-34 ATP from electron transport chain alone.
  • Total yield including Krebs and glycolysis: 30-38 ATP per glucose molecule.

Alternative ATP Production: Fermentation

• Used in absence of oxygen.
• Less efficient than aerobic respiration.

Importance of ATP Production

• Blocking ATP production (e.g., cyanide) can be lethal.
• Mitochondrial role in ATP production emphasizes research into mitochondrial diseases.

Conclusion

• Importance of understanding ATP production.
• Encouragement to stay curious and explore more.