TCA cycle is nothing but Krebs cycle ..the first step of Krebs cycle is formation of Citric acid which is condensation reaction between oxalo acetic acid and acetyl coA

Explanation:
The TCA cycle (also known as the Krebs cycle or citric acid cycle) is a series of chemical reactions that occur in the mitochondria of eukaryotic cells. The cycle is essential for energy production and the metabolism of macronutrients, such as carbohydrates, fats, and proteins.

Citric acid is the first compound of the TCA cycle:
The first compound of the TCA cycle is citric acid, also known as citrate. Citric acid is formed when acetyl-CoA combines with oxaloacetate to form citrate. The reaction is catalyzed by the enzyme citrate synthase.

The steps of the TCA cycle:
The TCA cycle is a series of eight chemical reactions that occur in the mitochondria of eukaryotic cells. The steps of the TCA cycle are as follows:

1. Citrate synthase catalyzes the reaction between acetyl-CoA and oxaloacetate to form citrate.
2. Aconitase catalyzes the conversion of citrate to isocitrate.
3. Isocitrate dehydrogenase catalyzes the conversion of isocitrate to alpha-ketoglutarate.
4. Alpha-ketoglutarate dehydrogenase catalyzes the conversion of alpha-ketoglutarate to succinyl-CoA.
5. Succinyl-CoA synthetase catalyzes the conversion of succinyl-CoA to succinate.
6. Succinate dehydrogenase catalyzes the conversion of succinate to fumarate.
7. Fumarase catalyzes the conversion of fumarate to malate.
8. Malate dehydrogenase catalyzes the conversion of malate back to oxaloacetate, completing the cycle.

Conclusion:
In conclusion, the first compound of the TCA cycle is citric acid, which is formed when acetyl-CoA combines with oxaloacetate. The TCA cycle is essential for energy production and the metabolism of macronutrients.