Question

Which one is amphibolic?
A. Glycolysis
B. ETC
C. Gluconeogenesis
D. Kreb’s cycle

Answer 1

Hint: During the biochemical reaction occurring in living organisms larger molecules are converted into smaller molecules and from the smaller molecules larger molecules are biosynthesized. These two processes make the important metabolic pathways in a living organism.

Complete answer:
Several different chemical processes occur within the living organisms and are essential for interaction and production of various macromolecules such as proteins, nucleic acid, lipid etc.

Biochemical pathway involves catabolism and anabolism. Catabolism is the process of breaking down large molecules into smaller molecules to release energy. This is known as the degradative phase of metabolism. Anabolism is the formation of large and complex molecules from simple precursor molecules. It is regarded as the biosynthesis phase. When both anabolic and catabolic processes occur in a single pathway, the pathway is known as an amphibolic pathway.

During cellular respiration complex compounds are broken into simple molecules through a catabolic process to produce energy. This pathway is known as catabolic pathway. When the body requires energy acetyl coenzyme A is formed due to breaking of fatty acids and proteins which is the catabolic reaction of respiration. In the opposite condition when the body requires fatty acids or proteins the catabolic pathway stops and acetyl coenzyme A is used to form fatty acids through the anabolic pathway. Thus, the amphibolic pathway includes both catabolic and anabolic pathways.

> The Krebs cycle is an important amphibolic pathway as it includes both catabolic and anabolic processes. This cycle does both synthesis as well as breakdown activities. It functions in both degradative or catabolic and biosynthetic or anabolic reactions. The Krebs cycle is a series of reactions that breaks down acetyl coenzyme A to produce carbon dioxide and energy. This cycle produces NADH, H+, FADH. In addition to the degradation process it also leads to oxidation of certain substrates that generate energy for ATP production.

> The glycolysis is the process of breakdown of glucose into pyruvic acids and involves the catabolic process.

> Gluconeogenesis is a biosynthetic process that causes the formation of glucose from certain noncarbohydrates carbon substrates. It is an anabolic pathway.

> ETC or Electron transport chain is a series of complexes transferring electrons received by a final receptor. It follows a catabolic pathway.

Hence, the correct answer is option (D).

Note: The catabolism and anabolic pathway are important pathways which involve degradation and biosynthesis of molecules. In amphibolic pathways both catabolic and anabolic pathways exist together. Krebs cycle is an amphibolic pathway as degradation as well as oxidation of substrate takes place simultaneously.