Question

What is the amphibolic pathways? Explain with reference to respiratory pathway?

Answer 1

★ AMPHIBOLIC PATHWAY:-

→ Glucose is the favoured substrate for respiration.

→ Other substrates are also respired.

→ Fats breakdown into glycerol & fatty acids. Fatty acids are degraded to acetyl CoA and enter the pathway.

→ Glycerol is converted to PGAL and enters the pathway.

→ Proteins are degraded by proteases into amino acids.

→ Each amino acid (after deamination) enters the pathway at some stage within the Krebs' cycle or even as pyruvate or acetyl CoA.

→ The respiratory pathway is generally considered as a catabolic pathway. But it involves both anabolism and catabolism. So it is better called as an amphibolic pathway.

→ Example:- Fatty acids breakdown to acetyl CoA before entering the respiratory pathway. But when the organism needs to synthesise fatty acids, acetyl CoA withdraw from the respiratory pathway.

→ Similarly, during breakdown and synthesis of protein, respiratory intermediates are involved.