Lecture Notes on Aerobic Cellular Respiration

Introduction

• Discussion on morning routines and energy levels.
• Cells must constantly perform processes for survival using ATP (adenosine triphosphate).
• ATP is a nucleic acid with three phosphates, serving as the energy currency for cells.
• All cells, prokaryote or eukaryote, need to produce ATP.

Overview of Aerobic Cellular Respiration in Eukaryotic Cells

• Aerobic cellular respiration is a process of producing ATP, particularly in eukaryotic cells with organelles like the nucleus and mitochondria.
• Eukaryotic cells include protists, fungi, animals, and plants.
• Mitochondria are crucial for aerobic respiration as part of the process occurs there.

Process of Aerobic Cellular Respiration

Equation

• Reactants (inputs) are on the left and products (outputs) are on the right.
• Similar to photosynthesis, but not simply the reverse process.
• In photosynthesis: glucose is a product; in cellular respiration: glucose is broken down into ATP.

Steps of Aerobic Cellular Respiration

Step #1: Glycolysis

• Location: Cytoplasm
• Anaerobic process (does not require oxygen).
• Converts glucose into pyruvate.
• Net yield: 2 pyruvate, 2 ATP, and 2 NADH.
• NADH is a coenzyme that helps transfer electrons.

Intermediate Step

• Pyruvate transported to mitochondrial matrix.
• Pyruvate is oxidized to acetyl CoA.
• Carbon dioxide is released, producing 2 NADH.

Step #2: The Krebs Cycle (Citric Acid Cycle)

• Location: Mitochondrial matrix.
• Aerobic process (requires oxygen for some reactions).
• Acetyl CoA enters the cycle.
• Produces 2 ATP, 6 NADH, and 2 FADH2 (another coenzyme).
• Carbon dioxide is released.

Step #3: Electron Transport Chain and Chemiosmosis

• Location: Inner mitochondrial membrane.
• Requires oxygen, an aerobic step.
• Electrons from NADH and FADH2 are transferred.
• Generates a proton gradient that powers ATP synthase.
• ATP synthase adds a phosphate to ADP to make ATP.
• Oxygen is the final electron acceptor, forming water (H2O).
• Produces 26-34 ATP molecules in this step alone.

Total ATP Yield

• Total estimate of 30-38 ATP per glucose molecule, considering all steps.
• Emphasized that the number is a range due to various factors.

Alternative Processes

• Fermentation: Cellular process in the absence of oxygen; less efficient than aerobic respiration.
• Cyanide can block electron transport chain, preventing ATP production, showcasing the critical nature of ATP.

Importance of Mitochondria

• Mitochondria are essential for ATP production.
• Research on mitochondrial diseases is important and ongoing.

Conclusion

• Encouragement for continued curiosity and research into cellular processes and mitochondrial functions.