Lecture Notes: Cellular Respiration and ATP Production

Introduction

• Energy in Cells: Cells perform essential processes constantly, requiring energy in the form of ATP (Adenosine Triphosphate).
• ATP: A nucleic acid with three phosphate groups, essential for energy transfer in cells.
• Cellular Respiration: Process by which cells produce ATP.
  • Occurs in all cell types (prokaryotes and eukaryotes).
  • Specifically discussing aerobic cellular respiration in eukaryotic cells.

Aerobic Cellular Respiration in Eukaryotes

• Eukaryotic Cells: Have membrane-bound organelles like nuclei and mitochondria.
• Mitochondria: Key organelle for aerobic cellular respiration in eukaryotic cells.
• Goal: Produce ATP from glucose.

Aerobic Cellular Respiration Process

Overview

• Equation: Similar to photosynthesis but involves breaking down glucose to produce ATP.
• Dependency on Glucose: Essential for initiating the process, especially in germinating seeds and non-photosynthetic organisms.

Steps in Aerobic Cellular Respiration

Step 1: Glycolysis

• Location: Cytoplasm
• Nature: Anaerobic (does not require oxygen).
• Process: Glucose converted to pyruvate, producing 2 ATP and 2 NADH.
• NADH: A coenzyme that transfers electrons for further ATP production.

Intermediate Step

• Transport: Pyruvate transported into mitochondria.
• Conversion: Pyruvate oxidized to acetyl CoA, producing CO2 and NADH.

Step 2: Krebs Cycle (Citric Acid Cycle)

• Location: Mitochondrial matrix
• Nature: Aerobic, indirectly relies on oxygen.
• Products: 2 ATP, 6 NADH, 2 FADH2, and CO2 released.
• FADH2: A coenzyme similar to NADH.

Step 3: Electron Transport Chain and Chemiosmosis

• Location: Inner mitochondrial membrane
• Nature: Aerobic, requires oxygen.
• Process: Electrons transferred creating a proton gradient, driving ATP production via ATP synthase.
• Final Step: Oxygen combines with protons to form water.
• ATP Yield: Estimates range from 26-34 ATP molecules from this step alone.

Total ATP Production

• Total Yield: Including glycolysis and the Krebs cycle, varies from 30-38 ATP per glucose molecule.
• Variation: Depends on factors like the proton gradient and textbook interpretations.

Alternative Pathways

• Fermentation: Occurs in absence of oxygen, less efficient but still produces ATP.

Importance of ATP and Mitochondria

• ATP Production Efficiency: Critical for survival, targeted by some poisons like cyanide.
• Mitochondrial Diseases: Increasing research and understanding are essential for treatment advancements.

Conclusion

• Curiosity and Research: Continuous questioning and research are vital for scientific advancement.