The chemical composition of human cells includes proteins, fats and carbohydrates

The chemical composition of human cells includes proteins, fats and carbohydrates. human food must contain these substances. Indicate which of them can transform into each other and which cannot?

Carbohydrates and fats can be converted into each other. Proteins can also be broken down by the enzyme systems of the human body in order to obtain energy, which the body can then convert into intramolecular glucose bonds.

Only protein synthesis from fat and carbohydrate molecules alone is impossible, without the addition of additional nitrogen-containing sources necessary for this.