At Which Stage of Respiration Does the CO2 Release Take Place?

Carbon dioxide (CO₂) release takes place during the Krebs cycle, also known as the citric acid cycle or tricarboxylic acid (TCA) cycle. This is the second stage of cellular respiration, which occurs in the mitochondria of eukaryotic cells.

During the Krebs cycle, acetyl-CoA, derived from the breakdown of glucose, is combined with oxaloacetate to form citrate. As the cycle progresses, citrate undergoes a series of reactions that result in the release of CO₂ as a byproduct. Specifically, CO₂ is released in two steps of the cycle:

1. When isocitrate is converted to α-ketoglutarate.
2. When α-ketoglutarate is converted to succinyl-CoA.

These reactions are catalyzed by specific enzymes, and the released CO₂ is then transported out of the mitochondria and eventually out of the cell, where it is exhaled by the organism.

In summary, CO₂ is released during the Krebs cycle, which is a crucial part of cellular respiration that generates energy in the form of ATP.