Understanding Cellular Respiration and ATP

Aug 13, 2024

Lecture Notes: Cellular Respiration and ATP

Introduction

  • Cellular respiration is how cells derive energy from glucose.
  • The process involves breaking down glucose into ATP (adenosine triphosphate).
  • ATP is the energy currency of cells, similar to money for transactions.

Key Components

  • Glucose (C6H12O6): Main source of energy, broken down during cellular respiration.
  • Oxygen (O2): Required to convert glucose into energy, carbon dioxide (CO2), and water (H2O).
  • ATP (Adenosine Triphosphate): Stored form of energy used by cells.

ATP Structure and Function

  • Composed of adenine (a nitrogenous base), ribose (a sugar), and three phosphate groups.
  • Phosphates are unstable together; release energy when one is expelled, turning ATP into ADP (adenosine diphosphate).
  • Hydrolysis: Water used to separate phosphate group, releasing energy.

Cellular Respiration Process

  1. Glycolysis

    • Occurs in the cytoplasm.
    • Converts glucose into 2 pyruvates, nets 2 ATP, and 2 NADH.
    • Anaerobic process (does not require oxygen).
    • In absence of oxygen, shifts to fermentation (produces lactic acid in muscles).

  2. Krebs Cycle (Citric Acid Cycle)

    • Takes place in the mitochondria.
    • Converts pyruvates into 2 ATP, CO2, and electron carriers (NADH & FADH2).
    • Introduced by Hans Krebs in 1937.
    • Aerobic process (requires oxygen).

  3. Electron Transport Chain

    • Occurs in mitochondria's inner membrane.
    • Utilizes NADH and FADH2 to pump protons and generate ATP.
    • Produces approximately 34 ATP molecules per glucose.

Overall ATP Yield

  • Total ATP from one glucose molecule: ~38 ATP, typically closer to 29-30 ATPs.
    • Glycolysis: 2 ATP
    • Krebs Cycle: 2 ATP
    • Electron Transport Chain: ~34 ATP

Conclusion

  • Cellular respiration is a vital biochemical process enabling cells to produce ATP.
  • Key stages include glycolysis, Krebs Cycle, and the electron transport chain.
  • Continuous research to fully understand the complex mechanisms involved.

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