Krebs' cycle starts with the formation of a six carbon compound by reaction between

Options

A. OAA and puruvic acid
B. OAA and Acetyl Co- A
C. Pyruvic acid and Acetyl Co-A
D. OAA and citrate synthetase

Answer

**Step-by-Step Text Solution:**

1. **Understanding the Krebs Cycle**: The Krebs cycle, also known as the citric acid cycle or tricarboxylic acid (TCA) cycle, is a crucial metabolic pathway that takes place in the mitochondria of cells. It plays a significant role in cellular respiration.

2. **Components Involved**: The cycle begins with the combination of two key components: acetyl coenzyme A (acetyl CoA) and oxaloacetic acid.
- Acetyl CoA is a 2-carbon compound.
- Oxaloacetic acid is a 4-carbon compound.

3. **Formation of Citric Acid**: When acetyl CoA (2 carbons) combines with oxaloacetic acid (4 carbons), they undergo a reaction catalyzed by the enzyme citrate synthase. This reaction results in the formation of citric acid, which is a 6-carbon compound.

4. **Conclusion**: Therefore, the Krebs cycle starts with the formation of a six-carbon compound (citric acid) by the reaction between acetyl coenzyme A and oxaloacetic acid.

5. **Answer**: The correct answer to the question is that the Krebs cycle starts with the formation of a six-carbon compound by the reaction between **oxaloacetic acid and acetyl coenzyme A**.

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