2.2.5—Glycosidic bonds

A glycosidic bond is a covalent link between sugar units. It joins monosaccharides into a disaccharide and, when the process repeats, into a polysaccharide.

1. Bring two monosaccharides together at suitable hydroxyl groups.
2. A condensation reaction forms the glycosidic bond and removes one molecule of water.
3. Repeating the joining process extends the carbohydrate chain; the bond type and position can differ, including α- or β-linked arrangements, but those details belong to the named molecule being formed.
4. Hydrolysis reverses the connection by adding water across the glycosidic bond, breaking a disaccharide into two monosaccharides or shortening a polysaccharide into smaller sugar units.

The bond is the stable covalent connection that lets cells assemble larger carbohydrate molecules for storage or structure. Hydrolysis makes the stored or dietary carbohydrate available as smaller sugars; the water molecule is a reactant in bond breakage, not just a solvent surrounding the molecule.

Do not reverse condensation and hydrolysis: condensation removes water to form the link, whereas hydrolysis uses water to break it. Do not assume every glycosidic bond has the same α/β orientation or position; identify those details only when the specific carbohydrate is in scope.