The number of time(s) decarboxylation of isocitrate occurs during single TCA cycle is
- Four
- One
- Two
- Three
Answer
(3) Two
Solution
As per NCERT, during the conversion of citric acid in the TCA cycle, it is first isomerised to isocitrate, which is followed by two successive steps of decarboxylation, leading to the formation of α-ketoglutaric acid and then succinyl-CoA.
Isocitrate α-ketoglutarate + CO2 (first decarboxylation)
⇒ α-Ketoglutarate succinyl-CoA + CO2 (second decarboxylation)
∴ In a single TCA cycle, starting from isocitrate, decarboxylation occurs two times.
Answer: (3)