Sucrose is formed by linking which two monosaccharides?

• A. Glucose and Fructose
• B. Glucose and Glucose
• C. Galactose and Glucose
• D. Fructose and Galactose

Answer: (A)

Form a disaccharide by linking two monosaccharides through a glycosidic bond, specifically using the anomeric carbons. Sucrose is made from glucose and fructose, with the bond between the C1 of glucose and the C2 of fructose (an α-1,2 linkage). Because both anomeric carbons are tied up in this bond, there’s no free carbonyl group left to act as a reducing end, so sucrose is a non-reducing sugar. The other pairings correspond to different common disaccharides: glucose with glucose gives maltose, galactose with glucose gives lactose, and fructose with galactose isn’t the standard pair for a common disaccharide.