Question 23.2: Complete oxidation of glucose produces six molecules of carb...
Complete oxidation of glucose produces six molecules of carbon dioxide. Describe the stage of catabolism at which each one is formed.
ANALYSIS Look at each stage of catabolism for the complete oxidation of glucose to carbon dioxide. Notice how many molecules of carbon dioxide are produced and by which step. Pathways to consider (in order) are glycolysis, conversion of pyruvate to acetyl-SCoA, and the citric acid cycle. (There is no need to consider oxidative phosporylation since glucose is completely oxidized at the end of the citric acid cycle.)
No molecules of carbon dioxide are produced during glycolysis. Conversion of one molecule of pyruvate to one molecule of acetyl-SCoA yields one molecule of carbon dioxide. In the citric acid cycle, two molecules of carbon dioxide are released for each molecule of acetyl-SCoA oxidized. One is released in Step 3 when isocitrate is converted to α-ketoglutarate and the other when α-ketoglutarate is converted to succinyl-SCoA in Step 4. Since each glucose molecule produces two pyruvate molecules, the total is three molecules twice, or six molecules of carbon dioxide.