Which of the following show correct order of electrons in mitochondria?

Options

A. `FeSrarrNADHrarrCoQrarrCyt" b"rarrFeSrarrCyt c_(1)rarrCyt" c"rarrCyt a_(3)rarrO_(2)rarrCyt" b"`
B. `NADHrarrFMNrarrFeSrarrCoQrarrCyt" b"rarrFeSrarrCyt c_(1)rarrCyt" c"rarrCyt" a"rarrCyt a_(3)rarrO_(2)`
C. `NADHrarrCyt c_(1)rarrCyt" c"rarrCyt" a"rarrCyt a_(3)rarrO_(2)rarrFMNrarrFeSrarrCoQrarrCyt" b"rarrFeS`
D. `Cyt c_(1)rarrCyt" c"rarrCyt" a"rarrCyt a_(3)rarrNADHrarrFMNrarrFeSrarrCoQrarrCyt" b"rarrFeSrarr2`

Answer

To determine the correct order of electron flow in mitochondria, we need to understand the sequence of electron transport through the electron transport chain (ETC). The ETC is a series of protein complexes and other molecules that transfer electrons from electron donors to electron acceptors via redox reactions. Here’s a step-by-step breakdown of the correct order:

### Step-by-Step Solution:

1. **Start with NADH**: The process begins with NADH, which donates electrons to the electron transport chain. This is the first step in the sequence.

2. **NADH Dehydrogenase Complex (Complex I)**: The electrons from NADH are transferred to the NADH dehydrogenase complex (also known as Complex I). This is where the first transfer occurs.

3. **Ubiquinone (Coenzyme Q)**: After Complex I, the electrons are passed on to Ubiquinone (Coenzyme Q). This molecule acts as a mobile electron carrier within the inner mitochondrial membrane.

4. **Cytochrome b (Complex III)**: Next, the electrons move to Complex III, where they are transferred to cytochrome b.

5. **Cytochrome c1**: From cytochrome b, the electrons are then transferred to cytochrome c1, which is part of the same complex.

6. **Cytochrome c**: The electrons continue to cytochrome c, another mobile carrier that shuttles electrons between Complex III and Complex IV.

7. **Cytochrome a and a3 (Complex IV)**: The electrons are then passed to cytochrome a and cytochrome a3, which are part of Complex IV.

8. **Oxygen (O2)**: Finally, the electrons are transferred to molecular oxygen (O2), which is the terminal electron acceptor. Oxygen combines with protons (H+) to form water (H2O).

### Summary of the Correct Order:
- NADH → NADH Dehydrogenase (Complex I) → Coenzyme Q (Complex II) → Cytochrome b (Complex III) → Cytochrome c1 → Cytochrome c → Cytochrome a → Cytochrome a3 (Complex IV) → O2

### Conclusion:
The correct order of electron flow in mitochondria is: **NADH → Coenzyme Q → Cytochrome b → Cytochrome c1 → Cytochrome c → Cytochrome a → Cytochrome a3 → O2**.