Veterinary Biochemistry & Metabolism

Chitin, found in fungal cell walls and arthropod exoskeletons, is an unbranched polymer consisting solely of N-acetyl-D-glucosamine (GlcNAc) units joined by $\beta-(1\rightarrow 4)$ glycosidic bonds.

Inulin is a naturally occurring storage fructan polysaccharide consisting of linear chains of D-fructose units linked by $\beta-(2\rightarrow 1)$ glycosidic bonds, often terminating with a glucose residue.

Carbohydrates are chemically defined as polyhydroxy aldehydes or ketones (D), originally described empirically as hydrates of carbon with general formula $C_n(H_2O)_n$ (C), containing a minimum of three carbons (trioses like glyceraldehyde/dihydroxyacetone) (A). Polyhydroxy alcohols without carbonyl groups (like glycerol or sorbitol) are sugar alcohols (alditols), not true carbohydrates.