Number of shuttles for transportion extra mimtochondrial `NADH_(2)` into mitochondrial is

Options

A. 1
B. 2
C. 3
D. 0

Answer

To determine the number of shuttles for the transportation of extra mitochondrial NADH into the mitochondria, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Problem**: The question asks for the number of shuttles that transport extra mitochondrial NADH into the mitochondria.

2. **Identify the Barrier**: Recognize that NADH cannot pass through the inner mitochondrial membrane directly because it is impermeable to NADH and NAD+.

3. **Define Mitochondrial Shuttles**: Mitochondrial shuttles are systems that facilitate the transport of reducing agents like NADH across the inner mitochondrial membrane.

4. **List the Main Shuttle Systems**: In humans, there are two primary shuttle systems responsible for transporting NADH into the mitochondria:
- **Glycerol Phosphate Shuttle**
- **Malate-Aspartate Shuttle**

5. **Explain Each Shuttle**:
- **Glycerol Phosphate Shuttle**: This shuttle helps regenerate NAD+ from NADH and is involved in the transport of electrons derived from glycolysis.
- **Malate-Aspartate Shuttle**: This is a more efficient shuttle that also transfers electrons and regenerates NAD+.

6. **Conclusion**: Since there are two main shuttles that transport extra mitochondrial NADH into the mitochondria, the answer to the question is **2**.

### Final Answer:
The number of shuttles for the transportation of extra mitochondrial NADH into the mitochondria is **2**.

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