Notes on Aerobic Cellular Respiration

Introduction

• Discussion on energy levels, comparing human morning energy to cellular energy demands.
• Importance of ATP (Adenosine Triphosphate) as the energy currency for cells.

What is ATP?

• ATP is a type of nucleic acid with three phosphates.
• Cells must produce ATP regardless of being prokaryotic or eukaryotic.

Aerobic Cellular Respiration

• Focus on eukaryotic cells which have membrane-bound organelles.
• Eukaryotic cells include protists, fungi, animals, and plants.
• Mitochondria play a crucial role in aerobic cellular respiration.

Overall Reaction Equation

• Reactants on the left, products on the right.
• Similarities to photosynthesis in terms of reactants and products being on different sides.
• Glucose is a key component: produced in photosynthesis, broken down in cellular respiration.
• For example, germinating beans rely on stored glucose before they can photosynthesize.

Steps of Aerobic Cellular Respiration

Step 1: Glycolysis

• Occurs in the cytoplasm and does not require oxygen (anaerobic).
• Converts glucose into pyruvate.
• Net yield: 2 pyruvate, 2 ATP, and 2 NADH.
• NADH is a coenzyme that transfers electrons.

Step 2: Intermediate Step

• 2 pyruvate are transported into the mitochondria and oxidized into 2 acetyl CoA.
• Carbon dioxide is released and 2 NADH are produced.

Step 3: Krebs Cycle (Citric Acid Cycle)

• Takes place in the mitochondrial matrix and is aerobic.
• Involves 2 acetyl CoA and produces:
  • 2 ATP
  • 6 NADH
  • 2 FADH
• FADH is another coenzyme, similar to NADH.

Step 4: Electron Transport Chain and Chemiosmosis

• Occurs within the inner mitochondrial membrane and requires oxygen.
• Electrons are transferred from NADH and FADH to electron carriers.
• Creates a proton gradient that powers ATP synthase.
• Oxygen acts as the final electron acceptor, forming water (H2O).

ATP Yield

• ATP production can vary:
  • Electron transport chain and chemiosmosis yield approximately 26-34 ATP per glucose.
  • Total yield from all steps ranges from 30 to 38 ATP molecules per glucose.

Alternative Pathways

• In absence of oxygen, some cells perform fermentation, which is less efficient for ATP production.

Importance of ATP Production

• Cyanide can block ATP production by interfering with the electron transport chain.
• Research on mitochondrial diseases is crucial due to the importance of mitochondria in ATP production.

Conclusion

• Encouragement to stay curious and continue learning.