Answer to Question #274194 in Biochemistry for Water

Question

In three separate experiments of Krebs cycle, pyruvate labeled with 14 C at C-1, at C-2, or at C-3 is metabolized via the pyruvate dehydrogenase complex and the citric acid cycle. 

a.Which labeled pyruvate molecule is the first to yield 14 CO2 ? 

b.Which is the last to yield 14 CO2 ?

c.How many turns of the cycle are required to release all of the labeled carbon atoms as 14 CO2 ?

Answer 1

Pyruvate—three carbons—is converted to acetyl CoA, a two-carbon molecule attached to coenzyme A. A molecule of coenzyme A is a necessary reactant for this reaction, which releases a molecule of carbon dioxide and reduces a NAD+ to NADH.