What sort of conclusions can be made based on this information given? Why is it
ID: 206886 • Letter: W
Question
What sort of conclusions can be made based on this information given? Why is it that the wildtype intermediates are radiolabeled and not the mutant intermediates?
I isolate mitochondria from wildtype (WT) and mutant liver cells, and provide them with radiolabeled pyruvate (all three carbons of pyruvate are radiolabeled). I then measure the levels of radiolabeled TCA intermediates (including Acetyl CoA) that are generated. In wildtype cells, all the intermediates become radiolabeled. However, in the mutant, NONE of the intermediates are radiolabeled.Explanation / Answer
Answer) Pyruvate has to pass through the mitochondrial inner membrane to reach its matrix where pyruvate oxidation takes place. pyruvate oxidation is carried out by pyruvate dehydrogenase. only after the oxidation, pyruvate can be converted into other intermediates of TCA cycle.
if a mutant mitochondrion does not show any TCA intermediates, it indicates that either the entry of Pyruvate to the mitochondrial matrix is restricted or the pyruvate dehydrogenase has become non-functional and therefore no oxidation of pyruvate.
It is more likely that the Pyruvate dehydrogenase in the mitochondria got some mutations which prevent the oxidation of pyruvate by this enzyme. and no further TCA intermediates are formed.
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