Answer to Question #9081 in Biochemistry for Daisy

Answer to Question #9081 in Biochemistry for Daisy


Question #9081

Explain how an animal that persists on a diet composed of 90% protein, 7% fat, and 3% carbohydrate utilizes food of this composition to maintain itself and grow

Expert’s answer

This diet is unusual for animals and results in numerous changes inmetabolism. Carbohydrates (a usual source of energy for animal) arevery few in this diet, thus carbohydrates cannot serve as a majorenergy source. Thus, energy is extracted from proteins. 1g of proteincontain almost the same amount of energy as 1g of carbohydrates,however digestion of proteins is much more difficult. In the stomachand intestine proteins are split to aminoacids; this aminoacids go toevery cell of the organism through the blood. Decomposing ofaminoacids involves complicated system of chemical reactions, thecentral part of this reactions is citric acid cycle. Most ofaminoacids are splitted to acetyl-CoA and during this process giveenergy in form of ATP and NAD(P)H. Next, acetyl-CoA molecules canserve as a source of energy (in the citric acid cycle) or can be usedas building blocks for creating lipids and carbohydrates that arenecessary for organism. Thus, in this case proteins perform functionsnormally attributed to carbohydrates and lipids. Finally, lipids fromfood become building blocks for steroid hormones, eicosanoids andspecific intra-cellular lipids.

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