Amphibolic Pathway - An Overview

“An amphibolic pathway is a biochemical pathway that includes both anabolic and catabolic processes.”

In 1961, B. Davis coined the term amphibolic pathway. A biochemical pathway, which involves both catabolism and anabolism is known as an amphibolic pathway. The amphibolic pathway can be best explained by Krebs’ cycle.

Generally, cellular respiration is the biochemical process of breaking down of glucose to release energy. Among the carbohydrates, glucose is the common substrate for energy production. Other compounds used for energy production include fats and proteins. But energy cannot be produced directly from these substrates hence they are formerly converted into simpler forms. For example, fats on lysis give glycerol and fatty acids. Fatty acids are converted to acetyl CoA whereas glycerol is transformed into 3-phosphoglyceraldehyde (PGAL) which then enter the respiratory pathway. Proteins break down into amino acids by the enzyme called proteases. Based on the type of amino acid they will either form pyruvate or acetyl-CoA or follow the Krebs’ cycle and complete the process of respiration.

Also Read: Kreb’s Cycle

Amphibolic Pathway

Respiration is the breakdown of the complex compounds into simple ones to produce energy molecule, ATP. Hence the process is called catabolic process and the pathway is termed as a catabolic pathway. Actually, respiration is the result of both making and breaking. When energy is required, proteins or fatty acids are broken down to form acetyl-CoA and further processes of respiration occur. This is catabolism. When the body requires fatty acids or proteins, respiratory pathway stops and the same acetyl-CoA is utilized and fatty acids are manufactured. This process of synthesis is termed as anabolism. Thus we can say respiration is the sum process of catabolism and anabolism. Products of the Krebs cycle and glycolysis act as a precursor for the synthesis of fats, proteins, etc. Hence, the respiratory pathway is known as an amphibolic pathway.

Also Read: Human Respiratory System

To know more about the amphibolic pathways, visit BYJU’S website.

Frequently Asked Questions


What is an amphibolic pathway?

An amphibolic pathway is the one that involves both catabolic and anabolic processes.


Is glycolysis an amphibolic pathway?

Glycolysis provides ATP and chemical intermediates to form biomolecules, hence it is an amphibolic pathway.


Why is respiration an amphibolic pathway?

Respiration involves both catabolism and anabolism. During fatty acid synthesis, acetyl coenzyme A is withdrawn from the respiratory pathway. Respiratory substrates get withdrawn during protein synthesis also.


Why is Kreb’s cycle an amphibolic pathway?

Kreb’s cycle involves both oxidative and synthetic process. The intermediates like oxaloacetate are used in the synthesis of biomolecules such as amino acids for protein formation.

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