What bond joins monosaccharides?

• A. Hydrogen bond
• B. Peptide bond
• C. Phosphodiester bond
• D. Glycosidic link

Answer: (D)

The bond that joins monosaccharides is the glycosidic linkage. It’s a covalent bond formed when a hydroxyl group on one sugar reacts with the anomeric carbon of another sugar, releasing a molecule of water in a condensation reaction. This creates an ether-type linkage between the sugar units. The orientation around the anomeric carbon can be alpha or beta, which influences the properties of the resulting carbohydrate (for example, starch has alpha linkages, cellulose has beta linkages). Hydrogen bonds are non-covalent interactions that help hold structures together but don’t form the actual link between sugar units. Peptide bonds connect amino acids, and phosphodiester bonds connect nucleotides in nucleic acids.