Question: 115: The 5-C compound formed during TCA cycle is:
(1) \alpha-ketoglutaric acid
(2) Oxalo succinic acid
(3) Succinic acid
(4) Fumaric acid
Answer: Option (1)
Explanation:
The tricarboxylic acid (TCA) cycle is a series of enzyme-catalyzed reactions involved in the oxidation of acetyl CoA.
During the TCA cycle, citric acid with 6 carbon atoms is converted into isocitric acid, which is also a 6-carbon compound.
Isocitric acid undergoes oxidative decarboxylation to form \alpha-ketoglutaric acid.
\alpha-ketoglutaric acid contains 5 carbon atoms and is the only 5-carbon compound formed in the TCA cycle.
Oxalosuccinic acid is a short-lived intermediate and also contains 6 carbon atoms.
Succinic acid and fumaric acid are both 4-carbon compounds formed later in the cycle.
Hence, the correct answer is \alpha-ketoglutaric acid.