Number of carbon-dioxide molecules after Krebs cycle

Question

Determine the number of carbon-dioxide molecules which are liberated after each cycle of Krebs cycle? For a single glucose how many carbon-dioxide molecules were already released by the aerobic respiration at that point?

Answer 1

Each and every round of the Krebs cycle releases two carbon dioxide molecules. At the end of the cycle each carbon atoms from the initial glucose molecule degraded in glycolysis are already released incorporated into carbon-dioxide molecules. That takes place as for each glucose two pyruvic acid molecules were made up by glycolysis. Each of such two pyruvic acids then is transformed into acetyl CoA with release of one carbon-dioxide molecule (two in total). As each of the two produced acetyl CoA cycles the Krebs cycle once, from the primary glucose two rounds of the Krebs cycle is produced and therefore four other carbon-dioxide molecules are formed.

All of the six carbons of glucose molecule are then integrated into six carbon-dioxide molecules (that is, two made through acetyl CoA formation and four through the two cycles of Krebs cycle).