Lecture Notes: Cellular Respiration and ATP Production

Morning Routine vs. Cellular Routine

• Lecturer compares personal morning routine needing coffee to cells being active all the time.
• Cells perform processes continuously, relying on ATP (adenosine triphosphate) for energy.

ATP (Adenosine Triphosphate)

• ATP is essential for energy transfer in cells.
• Composed of adenosine and three phosphate groups.

Importance of ATP Production

• All cells, prokaryotic and eukaryotic, must produce ATP.
• Aerobic cellular respiration is one method for ATP production, especially in eukaryotes.

Aerobic Cellular Respiration in Eukaryotic Cells

• Occurs in cells with membrane-bound organelles like mitochondria.
• Common in protists, fungi, animals, and plants.

Overall Equation for Aerobic Cellular Respiration

• Reactants (Inputs): On the left side (e.g., glucose and oxygen).
• Products (Outputs): On the right side (e.g., ATP, CO2, and H2O).
• Contrast with photosynthesis where glucose is a product.

Glucose Usage in Germinating Beans

• Germinating beans use stored glucose for cellular respiration before they can photosynthesize.

Step-by-Step Breakdown of Aerobic Cellular Respiration

Step 1: Glycolysis

• Location: Cytoplasm
• Requires Oxygen: No (Anaerobic)
• Process: Glucose is converted to pyruvate.
• Output: 2 pyruvate, 2 ATP, 2 NADH

Intermediate Step

• Location: Mitochondrial matrix
• Process: Pyruvate is oxidized to acetyl CoA.
• Output: 2 acetyl CoA, CO2, 2 NADH

Step 2: Krebs Cycle (Citric Acid Cycle)

• Location: Mitochondrial matrix
• Requires Oxygen: Indirectly
• Process: Acetyl CoA enters the cycle.
• Output: CO2, 2 ATP, 6 NADH, 2 FADH2

Step 3: Electron Transport Chain and Chemiosmosis

• Location: Inner mitochondrial membrane
• Requires Oxygen: Yes (Aerobic)
• Process: Electrons from NADH and FADH2 are transferred through protein complexes.
• Proton Gradient: Protons are pumped across the inner membrane.
• ATP Synthase: Enzyme that synthesizes ATP using the proton gradient.
• Output: Water (H2O) and a range of 26-34 ATP molecules.

Total Yield of ATP from Cellular Respiration

• Range: 30-38 ATP molecules per glucose molecule (including all steps).
• Varies due to several factors (e.g., proton gradient efficiency).

Anaerobic Respiration: Fermentation

• Performed when oxygen is not available.
• Produces ATP less efficiently than aerobic respiration.
• Important alternative for cells under anaerobic conditions.

Importance of ATP Production and Mitochondrial Health

• Cyanide can block ATP production by affecting the electron transport chain.
• Highlighted importance of ongoing research in mitochondrial diseases.

Conclusion

• Emphasis on the critical nature of ATP for cell function.
• Encouragement to stay curious and continue learning.