Biochemistry : Glycerolipids and Triglycerides

Study concepts, example questions & explanations for Biochemistry

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Example Questions

Example Question #14 : Lipid Classifications

In fat, which glycolysis metabolite is a reactant in single-step synthesis of glycerol 3-phosphate?

Possible Answers:



Dihydroxyacetone phosphate

Glyceraldehyde 3-phosphate


Correct answer:

Dihydroxyacetone phosphate


Glycerol phosphate can be created by the glycerol phosphate shuttle. Insects use this process in their muscles for flying, because they require quick ATP synthesis. To generate that ATP, the NADH synthesized during glycolysis ends up being regenerated into , and is shuttled over to the mitochondria to participate immediately in oxidative phosphorylation. Via the glycerol phosphate shuttle, NADH reduces dihydroxyacetone phosphate directly into glycerol phosphate, in a reaction that is catalyzed by glycerol 3-phosphate dehydrogenase. The metabolite here that can be recognized from glycolysis is the dihydroxyacetone phosphate. Phosphoenolpyruvate, pyruvate, and 3-phosphoglycerate are all indeed glycolysis metabolites, but none could be easily reduced to glycerol 3-phosphate. If you guessed glyceraldehyde 3-phosphate, you’d be close, because structurally, it appears that it could also be directly reduced to glycerol phosphate. Indeed, during glycolysis, it is interconverted to dihydroxyacetone phosphate. But the glycerol phosphate shuttle uses dihydroxyacetone phosphate; hence, the answer is dihydroxyacetone phosphate.

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