Ketone bodies

During fasting or with a carbohydrate restrictive diet, water-soluble ketone bodies are formed in the liver from the acetyl-CoA produced by fatty acid breakdown.

Triacylglycerols are the major storage form of metabolic energy in the body. A typical human body contains more than 100 times as many kilocaries stored as triacylglycerols in adipose tissue than in glycogen storage in the liver and muscle. The breakdown of triacylglycerols for use as energy begins with hydrolysis. The glycerol unit enters energy metabolism as dihydroxyacetone phosphate while the carbons from the fatty acid portions enter as acetyl CoA. The process of fatty acid degradation involves sequential removal of two-carbon units in a series of reactions called β-oxidation.

WikiPremed Resources

Learning Goals


Be able to describe hormonal triggers and primary signaling system for hydrolysis of triglycerides by lipases.

Understand the pathway by which glycerol is readily interconvertible with the glycolytic intermediate dihydroxyacetone phosphate.

Identity the role of carnitine in fatty acid metabolism.

Be capable of describing the structural changes that occur upon an acyl CoA molecule step by step proceeding through a round of the β-oxidation pathway beginning with oxidation by FAD and ending with thiolysis.

Understand the factors that lead to production of ketone bodies, the reactions involved in their synthesis, and their role in metabolism.

Suggested Assignments

The question server contains a general section covering basic concepts from gluconeogenesis, the pentose phosphate pathway, glyocogen metabolism, fatty acid metabolism, the urea cycle, and metabolic integration. After review complete the crossword puzzle for energy metabolism. Here is the solution to the puzzle.

Read pp. 72-74 in ExamKrackers Biology I.

Review the web resources for fatty acid metabolism.

Conceptual Vocabulary for Fatty Acid Metabolism