Question

Which linkage joins the monosaccharide units in sucrose?

• A. \(C_1 - C_4\) glycosidic linkage
• B. \(C_1 - C_2\) glycosidic linkage
• C. \(C_1 - C_6\) glycosidic linkage
• D. \(C_2 - C_4\) glycosidic linkage

Hint:

Sucrose consists of \(\alpha\)-D-glucose and \(\beta\)-D-fructose joined by a \(C_1-C_2\) glycosidic bond. Since both anomeric carbons participate in bonding, sucrose is a non-reducing sugar.

Answer 1

The Correct Option is B

Concept: Sucrose is a disaccharide composed of two monosaccharide units:
• \(\alpha\)-D-glucose
• \(\beta\)-D-fructose These two units are connected through a glycosidic bond.

Step 1: Identify the carbon atoms involved. In sucrose:
• The \(C_1\) carbon of \(\alpha\)-D-glucose
• The \(C_2\) carbon of \(\beta\)-D-fructose form the glycosidic linkage.

Step 2: State the type of linkage. Thus, sucrose contains a \[ C_1 - C_2 \] glycosidic bond between glucose and fructose.

Step 3: Explain why sucrose is non-reducing. Both reducing groups of glucose and fructose are involved in bond formation, so no free aldehyde or ketone group remains. Hence, sucrose is a non-reducing sugar. \[ \boxed{C_1 - C_2 \text{ glycosidic linkage}} \]