Macromolecules for the biosynthesis and energy stores have to be formed. They have a limited range of substrates available for catabolism, and they are almost exclusively carbohydrates. Degradation products produced by carbohydrate catabolism in parasites are usually in the form of complex organic acids, whereas in mammals complete degradation produces carbon dioxide and water as the waste products. In mammals, energy metabolism consists of a number of components, Glycolysis, Krebs cycle, and the cytochrome system. Therefore it is a very rich energy source.
Parasites have a dilemma .
Those helminths which are CO 2 fixers can be categorized by the type of end products they produce. Acetate and Propionate Producers 2. Fatty acids have lower dissociation constants than lactic or succinate, they are weaker acids and are therefore less toxic to the parasite and host. The principal energy source is glucose. Glycolytic enzymes are not free in the cytoplasm, but contained in special membrane bound microbodies bodies called glycosomes .