What type of bond joins two monosaccharides to form a disaccharide?

• A. Glycosidic bonds
• B. Peptide bonds
• C. Phosphodiester bonds
• D. Hydrogen bonds

Answer: (A)

Joining two monosaccharides to form a disaccharide occurs through a glycosidic bond, a covalent linkage created by a dehydration synthesis between a hydroxyl group on one sugar and the anomeric carbon of the other. This C-O-C bond (an ether linkage) is the specific connection that holds the two sugar units together. Hydrogen bonds can help stabilize the overall structure but do not create the covalent linkage; peptide bonds link amino acids in proteins; phosphodiester bonds connect nucleotides in nucleic acids. So the glycosidic bond is the correct mechanism for forming a disaccharide.