A single turn of the citric acid cycle yields

Options

A. `2 FADH_2, 2 NADH_2, 2 GTP`
B. `1 FADH_2, 2 NADH_2, 1 GTP`
C. `1 FADH_2, 3 NADH_2, 1 GTP`
D. `1 FADH_2, 4 NADH_2, 1 GTP`

Answer

To solve the question regarding the products yielded from a single turn of the citric acid cycle, we will analyze the cycle step by step.

### Step 1: Understanding the Citric Acid Cycle
The citric acid cycle, also known as the tricarboxylic acid (TCA) cycle or Krebs cycle, is a key metabolic pathway that plays a crucial role in cellular respiration. It takes place in the mitochondria and involves a series of chemical reactions that convert acetyl-CoA into energy.

### Step 2: Starting the Cycle
The cycle begins with the condensation of an acetyl group (from acetyl-CoA) with oxaloacetate to form citrate (citric acid). This is the first step of the cycle.

### Step 3: Key Reactions and Products
As the cycle progresses, several key reactions occur:
- **Decarboxylation Reactions**: Two carbon dioxide (CO2) molecules are released during the cycle. Each decarboxylation reaction also produces one molecule of NADH.
- **Formation of GTP**: One molecule of GTP (or ATP, depending on the cell type) is produced during the conversion of succinyl-CoA to succinate.
- **FADH2 Production**: One molecule of FADH2 is produced during the conversion of succinate to fumarate.
- **NADH Production**: In total, three molecules of NADH are produced during the cycle.

### Step 4: Summary of Products
From one complete turn of the citric acid cycle, the following products are generated:
- 3 NADH
- 1 FADH2
- 1 GTP (or ATP)
- 2 CO2 (released as waste)

### Conclusion
Thus, the answer to the question "A single turn of the citric acid cycle yields" is:
- 3 NADH
- 1 FADH2
- 1 GTP

### Final Answer
The correct option is: **3 NADH, 1 FADH2, and 1 GTP.**

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