Question

Fat has two components, glycerol and fatty acids. They enter common pathway of respiration as

• A. DiHAP and $\alpha$-ketoglutarate
• B. DiHAP and acetyle CoA
• C. Glyceric acid and acetyl CoA
• D. Glyceric acid and $\alpha$-ketoglutarate

Answer 1

The correct option is B DiHAP and acetyle CoA

When fats are the respiratory substrates, they are first converted to fatty acids and glycerol in the presence of enzyme lipase. Glycerol is phosphorylated to glycerol-3-phosphate in the presence of enzyme glycerol kinase.

Glycerol + ATP → Glycerol-3-phosphate + ADP

Glycerol-3-phosphate is then converted to dihydroxyacetone phosphate by enzyme glycerol phosphate dehydrogenase which enters into glycolysis.

Glycerol-3-phosphate + NAD⁺ → Dihydroxyacetone phosphate + NADH + H⁺

^{The fatty acids are converted to acetyl coenzyme A by beta oxidation. The acetyl coenzyme A enters into Krebs cycle and oxidised to carbon dioxide and water.}

^{Thus, the correct answer is option B.}