Why is glycerol metabolized before fatty acids?

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Multiple Choice

Why is glycerol metabolized before fatty acids?

Glycerol is water-soluble, which means it can travel freely in the bloodstream and be readily taken up by cells, especially in the liver. Once inside the liver, glycerol is quickly converted to glycerol-3-phosphate by glycerol kinase and then to dihydroxyacetone phosphate (DHAP), an intermediate of glycolysis. From there it can feed into energy production or gluconeogenesis without needing special transport or activation steps. Fatty acids, on the other hand, are hydrophobic and rely on binding to albumin for transport, activation to acyl-CoA in the cytosol, and a mitochondrial carnitine shuttle to enter beta-oxidation. This sequence is more complex and slower, so glycerol is metabolized first because it can be rapidly funneled into central metabolism. The other statements don’t fit: glycerol isn’t more energy-rich than fatty acids, and the reason glycerol is prioritized isn’t about being less reactive or being unable to be metabolized later.

Glycerol is water-soluble, which means it can travel freely in the bloodstream and be readily taken up by cells, especially in the liver. Once inside the liver, glycerol is quickly converted to glycerol-3-phosphate by glycerol kinase and then to dihydroxyacetone phosphate (DHAP), an intermediate of glycolysis. From there it can feed into energy production or gluconeogenesis without needing special transport or activation steps.

Fatty acids, on the other hand, are hydrophobic and rely on binding to albumin for transport, activation to acyl-CoA in the cytosol, and a mitochondrial carnitine shuttle to enter beta-oxidation. This sequence is more complex and slower, so glycerol is metabolized first because it can be rapidly funneled into central metabolism.

The other statements don’t fit: glycerol isn’t more energy-rich than fatty acids, and the reason glycerol is prioritized isn’t about being less reactive or being unable to be metabolized later.

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