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Radioactive labeling experiments can yield estimates of how much glucose 6-phosp

ID: 279556 • Letter: R

Question

Radioactive labeling experiments can yield estimates of how much glucose 6-phosphate is metabolized by the pentose phosphate pathway and how much is metabolized by the combined action of glycolysis and the TCA cycle. Suppose that you have 2 samples of different tissues as well as 2 radioactively labeled glucose samples, one with glucose labeled with 14C at C-1 and the other with glucose labeled with 14C at C-6. Design an experiment that would enable you to determine the relative activity of the aerobic metabolism of glucose compared with metabolism by the pentose phosphate pathway. What results would you expect?

Explanation / Answer

Interpretation:

In pentose phosphosphate pathway only C-1 is decarboxylated and in glycolytic pathway, Krebs cycle, pyruvate dehydrogenase complex C-1 and C-6 are equally decarboxylated. From this we can easily determine relative activity of the aerobic metabolism of glucose compared with metabolism by the pentose phosphate pathway.