Question:medium
Thiamine deficiency causes decreased energy production because:
Thiamine deficiency causes decreased energy production because:
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Think about which oxidative decarboxylations feed and drive the TCA cycle.
Updated On: Jun 24, 2026
- It is required for the process of transamination
- It is a co-factor in oxidative reduction
- It is a co-enzyme for transketolase in the pentose phosphate pathway
- It is a co-enzyme for pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase
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The Correct Option is D
Solution and Explanation
Frame the answer around what actually generates ATP. Energy production hinges on getting carbon into the citric acid cycle and keeping that cycle turning, and thiamine pyrophosphate is the indispensable coenzyme at the two oxidative decarboxylation gates of that flow. The first gate is pyruvate dehydrogenase, which converts pyruvate from glycolysis into acetyl-CoA so it can enter the cycle. The second is alpha-ketoglutarate dehydrogenase, an enzyme inside the cycle itself that drives the conversion of alpha-ketoglutarate to succinyl-CoA. When B1 is deficient, both reactions falter, pyruvate accumulates (clinically seen as lactic acidosis), the cycle slows, and the supply of reducing equivalents to the electron transport chain dries up, cutting ATP. The remaining choices fail on specifics: transamination is a pyridoxal-phosphate job, thiamine is not a generic redox cofactor, and although transketolase is TPP-dependent it works in the non-oxidative arm of the pentose phosphate pathway and is used mainly to test thiamine status rather than to make energy.
\[\boxed{\text{Coenzyme for pyruvate and alpha-ketoglutarate dehydrogenase}}\]
\[\boxed{\text{Coenzyme for pyruvate and alpha-ketoglutarate dehydrogenase}}\]
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