Fuel Metabolism Summary

Having discussed the metabolism of the three major classes of organic molecules, we can now briefly review how each class is related to the others and to the process of synthesizing ATP. Figure 4-32, which is an expanded version of Figure 4-18, illustrates the major pathways we have discussed and the relations of the common intermediates. All three classes of molecules can enter the Krebs cycle through some intermediate, and thus all three can be used as a source of energy for the synthesis of ATP. Glucose can be converted into fat or into some amino acids by way of common intermediates such as pyruvate, oxaloacetate, and acetyl coenzyme A. Similarly, some amino acids can be

Vander et al.: Human Physiology: The Mechanism of Body Function, Eighth Edition

Protein Activity and Cellular Metabolism CHAPTER FOUR

Protein Activity and Cellular Metabolism CHAPTER FOUR

Protein

Amino acids

( Glycogen

Glucose

Fat it

Glycerol

Fatty acids

Amino acids

Glucose

Glycerol

Conversion Carbohydrates Fat

FIGURE 4-32

Interrelations between the pathways for the metabolism of carbohydrate, fat, and protein.

FIGURE 4-32

Interrelations between the pathways for the metabolism of carbohydrate, fat, and protein.

converted into glucose and fat. Fatty acids cannot be converted into glucose because of the irreversibility of the reaction converting pyruvate to acetyl coenzyme A, but the glycerol portion of triacylglycerols can be converted into glucose. Fatty acids can be used to synthesize portions of the keto acids used to form some amino acids. Metabolism is thus a highly integrated process in which all classes of molecules can be used, if necessary, to provide energy, and in which each class of molecule can provide the raw materials required to synthesize most but not all members of other classes.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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  • Ponto
    How protein converted to glucose?
    5 years ago

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