5-carbon dicarboxylic compound of Krebs cycle is

Options

A. Malate
B. Fumarate
C. Succinate
D. `alpha`-ketoglutarate.

Answer

To determine the 5-carbon dicarboxylic compound of the Krebs cycle, we can follow these steps:

### Step 1: Understand the Krebs Cycle
The Krebs cycle, also known as the citric acid cycle or TCA cycle, is a series of enzymatic reactions that play a crucial role in cellular respiration. It involves the oxidation of acetyl-CoA to produce energy.

### Step 2: Identify the Compounds in the Krebs Cycle
The main compounds involved in the Krebs cycle include:
- Citrate (6 carbons)
- Isocitrate (6 carbons)
- Alpha-ketoglutarate (5 carbons)
- Succinyl-CoA (4 carbons)
- Succinate (4 carbons)
- Fumarate (4 carbons)
- Malate (4 carbons)

### Step 3: Determine the 5-Carbon Dicarboxylic Acid
Among the compounds listed, we need to identify which one is a 5-carbon dicarboxylic acid. The options provided are:
- Malate (4 carbons)
- Fumarate (4 carbons)
- Succinate (4 carbons)
- Alpha-ketoglutarate (5 carbons)

### Step 4: Confirm the Correct Answer
Alpha-ketoglutarate is the only compound in the list that has 5 carbon atoms and contains two carboxylic acid groups (making it a dicarboxylic acid). Therefore, the correct answer is alpha-ketoglutarate.

### Conclusion
The 5-carbon dicarboxylic compound of the Krebs cycle is **alpha-ketoglutarate**.

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