In this article we will discuss about the interrelationships of metabolic path­ways .

A great variety of organic compounds can be derived from carbohydrates, lipids, and/or proteins. All organisms utilise the three major foodstuffs to form acetyl CoA or the metabolites of the Krebs cycle. These, in turn, supply energy upon subsequent oxida­tion by the cycle. A brief summary of the interrelationships of the metabolic path­ways is given in Fig. 8.91.

Interrelationships of Metabolic Pathways

Notice that one nonreversible reaction is the conversion of pyruvic acid to acetyl CoA. Thus an acetyl CoA molecule derived from fatty acid degradation cannot be directly transformed into pyruvic acid. There is, therefore, no direct route for the synthesis of carbohy­drates from fatty acids.


Plants and some microorganisms that can convert fatty acids to carbohydrates and proteins utilize a series of enzymic reactions not found in ani­mal tissues referred to as the glycolate cycle.