One molecule of `NADH + H^+//NADPH + H^+` has sufficient energy to generate 3 ATP through ETS. This energy is approximately

Options

A. 52.6 k cal
B. 21.9 k cal
C. 18 k cal
D. 36 k cal

Answer

To solve the question regarding the energy produced by one molecule of NADH + H⁺ in terms of ATP, follow these steps:

### Step-by-Step Solution:

1. **Understanding the Components**:
- NADH (Nicotinamide adenine dinucleotide) is a key electron carrier in cellular respiration.
- ATP (Adenosine triphosphate) is the primary energy currency of the cell.

2. **Energy Yield from NADH**:
- It is established that one molecule of NADH + H⁺ can generate approximately 3 ATP molecules through the electron transport system (ETS).

3. **Energy Value of ATP**:
- Each molecule of ATP is known to release approximately 7.3 kilocalories of energy when hydrolyzed.

4. **Calculating Total Energy from ATP**:
- Since one NADH + H⁺ produces 3 ATP, the total energy produced can be calculated as:
\[ \text{Total Energy} = \text{Number of ATP} \times \text{Energy per ATP} \]
\[ \text{Total Energy} = 3 \, \text{ATP} \times 7.3 \, \text{kcal/ATP} \]

5. **Performing the Calculation**:
- Now, calculate the total energy:
\[ \text{Total Energy} = 3 \times 7.3 = 21.9 \, \text{kcal} \]

6. **Conclusion**:
- Therefore, the energy produced by one molecule of NADH + H⁺ is approximately 21.9 kilocalories.

### Final Answer:
The energy produced by one molecule of NADH + H⁺ is approximately **21.9 kilocalories**.

---