Electrons from NADH produced in the mitochondrial matrix during TC A cycle are oxidised by complex I, and electrons are then transferred to

Options

A. Cytochrome `bc_(1)` complex
B. Cytochrome a and `a_(3)`
C. Cytochrome c
D. Ubiquinone

Explanation

To answer the question regarding where electrons from NADH produced in the mitochondrial matrix during the TCA cycle are transferred after being oxidized by complex I, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Role of NADH**:
- NADH is a key electron carrier produced during the TCA cycle (Krebs cycle) in the mitochondrial matrix. It carries electrons to the electron transport chain (ETC).

2. **Oxidation of NADH**:
- In the electron transport chain, NADH is oxidized by complex I (NADH dehydrogenase). This process releases electrons that are essential for ATP production.

3. **Electron Transfer from Complex I**:
- Once NADH is oxidized by complex I, the electrons are transferred to a molecule known as ubiquinone (also referred to as coenzyme Q or CoQ).

4. **Role of Ubiquinone (CoQ)**:
- Ubiquinone is a lipophilic (fat-soluble) molecule that plays a crucial role in the electron transport chain. It acts as a mobile electron carrier, shuttling electrons from complex I to complex III in the mitochondrial inner membrane.

5. **Final Answer**:
- Therefore, the electrons from NADH produced in the mitochondrial matrix during the TCA cycle are transferred to **ubiquinone (CoQ)**, also known as **UBQ9**.

### Final Answer:
Electrons from NADH produced in the mitochondrial matrix during the TCA cycle are oxidized by complex I and then transferred to **ubiquinone (CoQ or UBQ9)**.

---