Aerobic Cellular Respiration in Eukaryotic Cells

Introduction

• ATP (Adenosine Triphosphate): Main energy currency in cells
• Cells constantly need energy and therefore ATP
• Two types of cells: prokaryotes and eukaryotes
• This lecture focuses on aerobic cellular respiration in eukaryotic cells

Overview

• Organisms perform aerobic cellular respiration to produce ATP
• Eukaryotic cells include protists, fungi, animals, and plants
• Mitochondria: Key organelle in aerobic respiration

Aerobic Cellular Respiration Equation

• Reactants (Inputs): On the left side (e.g., glucose, O2)
• Products (Outputs): On the right side (e.g., CO2, H2O, ATP)
• Similar but not identical to photosynthesis
• Cellular respiration breaks down glucose to produce ATP

Steps of Aerobic Cellular Respiration

Step 1: Glycolysis

• Takes place in the cytoplasm
• Does not require oxygen (anaerobic process)
• Process: Glucose converted into pyruvate
• Outputs: ~2 ATP, 2 NADH, 2 pyruvate

Intermediate Step

• Pyruvate transported into mitochondria (mitochondrial matrix)
• Process: Pyruvate oxidized to acetyl CoA
• Outputs: 2 acetyl CoA, 2 NADH, CO2

Step 2: Krebs Cycle (Citric Acid Cycle)

• Takes place in mitochondrial matrix
• Considered an aerobic process (indirectly requires oxygen)
• Outputs: 2 ATP, 6 NADH, 2 FADH2, CO2

Step 3: Electron Transport Chain and Chemiosmosis

• Occurs in the inner mitochondrial membrane
• Requires oxygen (aerobic step)
• Process: Electrons transferred from NADH & FADH2 to protein complexes and electron carriers
  • Generates a proton gradient
  • Protons travel through ATP synthase, converting ADP to ATP
• Outputs: Water (H2O), large amount of ATP (26-34 ATP)

ATP Yield

• Variation in numbers of ATP produced per glucose molecule
• Estimate: 30-38 ATP per glucose molecule considering all steps
• Variables: Proton gradient, textbooks editions, etc.

Alternative Pathways

• Fermentation: For conditions with no oxygen, less efficient

Importance of ATP

• Example: Cyanide blocks electron transport chain, preventing ATP production
• Mitochondrial diseases and ongoing research

Conclusion

• Cellular respiration is crucial for ATP production in eukaryotic cells
• Continued research is vital for understanding and treating mitochondrial diseases

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Stay Curious!