Recording-2025-03-18T20:12:45.884Z.m4a

Key Products of Krebs Cycle:

• Each cycle produces:

  • 2 Carbon Dioxides

  • 1 ATP (via substrate level phosphorylation)

  • 3 NADHs

  • 1 FADH2

Role of Mitochondria:

• Central to cellular respiration

• NADH and FADH2 generated from glycolysis, acetyl CoA formation, and Krebs cycle are crucial for ATP production via oxidative phosphorylation.

Complex I of the Electron Transport Chain (ETC):

• NADH delivers electrons to Complex I.

• As electrons are transferred, NADH is oxidized to NAD+.

• Electrons transported lead to pumping protons (H+) across the membrane, creating a gradient.

Complex II:

• FADH2 provides its electrons to Complex II.

• Electrons are then transferred to coenzyme Q (CoQ).

• This stage is important for the conservation of energy across life forms.

Cytochrome c:

• Receives electrons from Complex II and transfers them to Complex IV.

• Acts as a mobile carrier within the membrane.

Complex IV:

• Final step where electrons are transferred to oxygen (O2), where it accepts electrons to form water (H2O).

• Essential for maintaining the flow of electrons in the chain.

Proton Gradient Creation:

• H+ ions are pumped from the mitochondrial matrix to the intermembrane space, creating a high concentration gradient.

• This gradient is key for ATP synthesis.

ATP Synthase Mechanism:

• The proton gradient drives ATP synthase, which spins to synthesize ATP from ADP and inorganic phosphate (Pi).

• A mechanical rotation facilitates ATP production.

Continuous ATP Production:

• ATP must be continually synthesized due to its instability and rapid consumption in active cells (e.g., muscle cells).

• There is a need for constant influx of NADH to keep the process ongoing.

Importance of Oxygen:

• Oxygen acts as the final electron acceptor in Complex IV.

• Essential for the efficient operation of aerobic respiration; without it, processes shift to anaerobic pathways such as fermentation.

Anaerobic Pathways:

• In the absence of oxygen, glycolysis can continue, resulting in pyruvate conversion to lactate or ethanol in microbes, allowing for minimal ATP production.

Amino Acids as Energy Source:

• Proteins can be broken down into amino acids, which can then enter the cellular respiration pathway when carbohydrates are unavailable.