If glucose, radioactively labeled in the C-2 position with ¹⁴C, is used as a substrate in a yeast extract maintained under strictly anaerobic conditions, what is the location of ¹⁴C in the product ethanol?

Question

Quizplus · Accepted Answer

In the process of fermentation, glucose is converted to pyruvate and then to ethanol. The radioactively labeled ¹⁴C from the C-2 position of glucose will be retained in the ethanol product, but it will be attached to the carbon that originally carried the aldehyde group of pyruvate in the reaction catalyzed by pyruvate decarboxylase. Therefore, the correct answer must include "CH₃-¹⁴CH₂" to indicate the position of the label on the carbon chain of the ethanol molecule. The only choice that contains this sequence in the correct position is B. Option A and C are incorrect because they do not have the labeled sequence in the correct position. Option D and E are incorrect because the radioactively labeled ¹⁴C will become part of the ethanol molecule.

If Glucose, Radioactively Labeled in the C-2 Position with 14C

If Glucose, Radioactively Labeled in the C-2 Position with ¹⁴C