What is the bond between two monosaccharides called?

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

Answer: (A)

The bond that links two monosaccharides is a glycosidic linkage, a covalent connection formed when the anomeric carbon of one sugar reacts with a hydroxyl group of the other sugar in a dehydration synthesis. This creates an O-glycosidic bond, and its specific orientation (alpha or beta) and carbon positions (such as 1→4, 1→2, etc.) define the particular disaccharide. For example, maltose has an alpha-1,4 glycosidic bond, lactose has a beta-1,4 bond, and sucrose has a glucose–fructose glycosidic linkage between different carbons. Other options don’t connect sugar units covalently: peptide bonds join amino acids, phosphodiester bonds link nucleotides in DNA/RNA, and hydrogen bonds are non-covalent interactions that help hold structures together without forming a covalent sugar–sugar bond.