Aerobic Cellular Respiration Overview

Aerobic Cellular Respiration

• Aerobic cellular respiration is the process cells use to break down glucose to make ATP, a crucial form of energy.
• It requires oxygen and occurs within the mitochondria of eukaryotic cells.
• All living organisms need ATP.

Steps of Aerobic Cellular Respiration

• Step #1: Glycolysis

  • Occurs in the cytoplasm.
  • An anaerobic process that doesn't require oxygen.
  • Breaks down glucose into pyruvate.
  • Net yield:
    • 2 pyruvate molecules
    • 2 ATP molecules
    • 2 NADH molecules. NADH carries electrons for later ATP production.

• Step #2: Intermediate Step

  • Pyruvate moves into the mitochondrial matrix.
  • Pyruvate is oxidized.
  • 2 pyruvate are converted to 2 acetyl CoA.
  • Carbon dioxide (CO2) is released.
  • 2 NADH molecules are produced.

• Step #3: Krebs Cycle (Citric Acid Cycle)

  • Takes place in the mitochondrial matrix.
  • An aerobic process, requiring oxygen to continue.
  • Acetyl CoA enters the cycle.
  • CO2 is released.
  • Produces:
    • 2 ATP molecules
    • 6 NADH molecules
    • 2 FADH2 molecules. FADH2 assists electron transfer for ATP production.

• Step #4: Electron Transport Chain and Chemiosmosis

  • Happens in the inner mitochondrial membrane.
  • An aerobic process.
  • Electron Transport: Electrons from NADH and FADH2 are passed to protein complexes and electron carriers.
  • Proton Gradient: Electron transfer pumps protons (H+) into the intermembrane space.
  • Electrochemical Gradient: The accumulation of H+ creates an electrical and chemical gradient.
  • ATP Synthase: H+ ions flow through ATP synthase, an enzyme.
  • ATP Production: The flow of H+ through ATP synthase drives ATP production.
  • Final Electron Acceptor: Oxygen acts as the final electron acceptor, forming water (H₂O).

ATP Production

• The majority of ATP comes from the electron transport chain and chemiosmosis.
• ATP yield varies based on conditions (e.g., efficiency of proton gradient).
• Estimated ATP produced from ETC and chemiosmosis range from 26 to 34 per glucose molecule.
• Overall estimations for total ATP per glucose molecule range from 30 to 38.

Comparisons to Photosynthesis

• The chemical equations for both processes are closely related.
• Photosynthesis uses CO₂ and H₂O to make glucose and O₂.
• Cellular respiration uses glucose and O₂ to produce CO₂, H₂O, and ATP.

Alternate ATP Production

• Fermentation: When oxygen is not available, cells use fermentation to create ATP. This process is less efficient.
• Importance of ATP Production: Cellular respiration is vital for all life.
  • Cyanide blocks the electron transport chain, halting ATP production.
  • Mitochondrial diseases disrupt mitochondrial function, leading to severe consequences.

This quiz explores the process of aerobic cellular respiration, detailing its significance in ATP production within eukaryotic cells. It covers the major steps, including glycolysis, the intermediate step, and the Krebs cycle, and emphasizes the role of oxygen in cellular metabolism. Test your knowledge on this essential biological process!