Inside an active mitochondrion, most electrons follow which pathway?

Options

A. Glycolysis`rarr`NADH`rarr`Oxidative Phosophorylation`rarr`ATP`rarrO_(2)`
B. Kreb's cycle`rarrFADH_(2)rarr`ETS`rarr`ATP
C. ETS`rarr`Kreb's cycle`rarr`ATP`rarrO_(2)`
D. Kreb's cycle`rarrNADH+H^(+)rarr`Electron transport chain`rarrO_(2)`

Answer

**Step-by-Step Solution:**

1. **Understanding Mitochondrial Function**: Mitochondria are known as the powerhouse of the cell, where energy production occurs through cellular respiration. The main processes involved are the Krebs cycle (citric acid cycle) and the electron transport chain (ETC).

2. **Electron Sources**: In an active mitochondrion, the primary sources of electrons are NADH and FADH2, which are produced during the Krebs cycle. These molecules carry high-energy electrons that are essential for the electron transport chain.

3. **Electron Transport Chain (ETC)**: The electrons from NADH and FADH2 enter the electron transport chain, which is located in the inner mitochondrial membrane. The ETC consists of a series of protein complexes and electron carriers that facilitate the transfer of electrons.

4. **Pathway of Electron Flow**: As electrons move through the electron transport chain, they are passed from one carrier to another, ultimately leading to the reduction of oxygen. Oxygen acts as the final electron acceptor in the chain.

5. **Formation of Water**: When oxygen accepts the electrons, it combines with protons (H+) to form water (H2O). This reaction is crucial as it helps maintain the flow of electrons through the chain.

6. **ATP Production**: The energy released during the electron transfer is used to pump protons across the mitochondrial membrane, creating a proton gradient. This gradient drives ATP synthesis through oxidative phosphorylation.

7. **Conclusion**: Therefore, inside an active mitochondrion, most electrons follow the pathway from NADH and FADH2 through the electron transport chain to oxygen, resulting in the formation of water and the production of ATP.

**Final Answer**: Most electrons inside an active mitochondrion follow the pathway from NADH and FADH2 through the electron transport chain to oxygen.

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