Lecture Notes: Aerobic Cellular Respiration in Eukaryotic Cells

Introduction

• Aerobic cellular respiration is crucial for ATP production in eukaryotic cells.
• ATP (Adenosine Triphosphate) is the energy currency of cells.
• Both prokaryotic and eukaryotic cells produce ATP, but the method differs.

ATP: The Energy Currency

• ATP: Adenosine Triphosphate, a nucleic acid with three phosphates.
• All cells must produce ATP; critical for cell processes.

Aerobic Cellular Respiration

• Specific focus on aerobic respiration in eukaryotic cells.
• Involves membrane-bound organelles: nucleus, mitochondria.
• Occurs in cells of protists, fungi, animals, and plants.

Overall Process

• Equation: Reactants (inputs) on the left, products (outputs) on the right.
• Similar to photosynthesis but not direct opposites.
• Glucose is broken down to make ATP.
• Example: Bean seed uses stored glucose for ATP production before photosynthesis.

Steps in Aerobic Cellular Respiration

Step 1: Glycolysis

• Location: Cytoplasm.
• Anaerobic process (does not require oxygen).
• Converts glucose to pyruvate.
• Net yield: 2 pyruvate, 2 ATP, 2 NADH.
• NADH: Coenzyme transferring electrons for ATP production.

Intermediate Step

• Pyruvate transported into mitochondrial matrix.
• Pyruvate oxidized to 2 Acetyl CoA.
• Release of CO2 and production of 2 NADH.

Step 2: Krebs Cycle (Citric Acid Cycle)

• Location: Mitochondrial matrix.
• Considered aerobic; indirectly relies on oxygen.
• Produces: 2 ATP, 6 NADH, 2 FADH2.
• FADH2: Coenzyme like NADH for electron transfer.

Step 3: Electron Transport Chain and Chemiosmosis

• Location: Inner mitochondrial membrane.
• Requires oxygen; complex process.
• Electrons from NADH and FADH2 create proton gradient.
• Protons pass through ATP synthase, generating ATP.
• Oxygen is the final electron acceptor (Water produced).
• Generates the majority of ATP.

ATP Production Estimates

• Range: 26-34 ATP produced in electron transport chain and chemiosmosis.
• Total ATP (including Krebs and glycolysis): 30-38 ATP per glucose molecule.
• Emphasis on range, not fixed number, due to variables like proton gradient.

Alternate Pathways and Considerations

• Fermentation as an alternative when oxygen is not available.
• Importance of ATP for cell survival; inhibition can be deadly (e.g., cyanide poisoning).
• Ongoing research into mitochondrial diseases.

Conclusion

• Making ATP is essential for cells.
• Continuous curiosity and research are crucial for advancements in biological sciences.

Stay curious and continue exploring the fascinating processes that sustain life!