Prokaryotic Cellular Respiration

• Prokaryotic Cells:

  • Perform cellular respiration, including the electron transport chain, using their plasma membranes for infolding.

Aerobic Cellular Respiration

• Catabolic Pathway:

  • Aerobic cellular respiration is catabolic, resulting in a negative free energy change (ΔG) because it releases ATP.

Glycolysis

• Universal Process:

  • Occurs in all cells, indicating its essential nature for energy metabolism.

Oxidation-Reduction Reactions

• Electron Loss:

  • When an electron is lost during a reaction, oxidation occurs. "Lose electron = oxidized."

ATP Production

• ATP Molecule:

  • Understanding the structure of ATP is crucial for understanding energy transfer in cells.

  • Aerobic cellular respiration yields a total of about 32 ATP, combining 28 (from oxidative phosphorylation) and 4 (from glycolysis).

Electron Transport Chain (ETC)

• Role of Oxygen:

  • Oxygen acts as the final electron acceptor in the ETC, which leads to water generation from electrons and hydrogen ions.

• Waste Products:

  • Carbon dioxide (CO2) is a waste product of this process.

Efficiency of Aerobic Respiration

• Exergonic Reaction:

  • A negative ΔG signifies that the process is exergonic (releases energy).

• Oxidative Phosphorylation:

  • Collects hydrogen ions through the ETC to generate a significant amount of ATP (28 ATP).

Krebs Cycle Insights

• Pyruvate Processing:

  • Pyruvate is converted into acetyl CoA, which enters the Krebs cycle. Each acetyl CoA allows two turns of the cycle, producing CO2, NADH, and FADH2.

  • Accumulated NADHs and FADHs contribute to ATP production.

ATP Yield from NADH and FADH2

• ATP Calculation:

  • Each NADH produces approximately 2.5 ATP; FADH2 produces 1.5 ATP (due to rounding, some sources list 2 and 2.5).

Difference in Organisms

• Phototrophs:

  • Both protists and plants (as well as some prokaryotes like bacteria) are phototrophs.

  • CO2, a waste product in respiration, is a key input for photosynthesis, while water, which is also a waste in respiration, is essential for photosynthesis.

  • Photosynthesis produces glucose, crucial for initiating cellular respiration.