Question

Which of the following statement options accurately describes the structural carbohydrate linkages present inside a standard molecule of Sucrose?

• A. It contains a standard C-1 to C-4 glycosidic bridge linking two identical \(\alpha\)-D-glucose rings together.
• B. It features a glycosidic linkage connecting the C-1 carbon of an \(\alpha\)-D-glucose unit to the C-2 carbon of a \(\beta\)-D-fructose unit.
• C. It consists of a C-1 to C-4 linkage binding a \(\beta\)-D-galactose ring directly onto a neighboring glucose molecule.
• D. It is formed by a continuous chain of \(\beta\)-D-glucose blocks linked entirely via C-1 to C-6 branch channels.

Hint:

Important disaccharides and their linkages:

• Sucrose \(=\) Glucose + Fructose \(\rightarrow \alpha(1 \rightarrow 2)\beta\)
• Maltose \(=\) Glucose + Glucose \(\rightarrow \alpha(1 \rightarrow 4)\)
• Lactose \(=\) Galactose + Glucose \(\rightarrow \beta(1 \rightarrow 4)\)

Answer 1

The Correct Option is B

Concept: Disaccharides are formed when two monosaccharides combine through a glycosidic linkage formed by a condensation reaction. Different disaccharides differ in:

• The monosaccharides involved
• The carbon atoms participating in the linkage
• The type of glycosidic bond formed

Step 1: Identify the monosaccharides present in sucrose.
Sucrose is a disaccharide composed of:

• One molecule of \(\alpha\)-D-glucose
• One molecule of \(\beta\)-D-fructose

Thus, sucrose is formed from glucose and fructose units.

Step 2: Determine the glycosidic linkage in sucrose.
In sucrose:

• The C-1 carbon of \(\alpha\)-D-glucose
• is linked to the C-2 carbon of \(\beta\)-D-fructose

Therefore, sucrose contains: \[ \alpha(1 \rightarrow 2)\beta \] glycosidic linkage. Since both anomeric carbons are involved in bond formation, sucrose behaves as a non-reducing sugar.

Step 3: Evaluate the options.

• [(A)] Incorrect — This describes maltose, which contains two glucose units linked by a C-1 to C-4 bond.
• [(B)] Correct — Sucrose contains a linkage between C-1 of \(\alpha\)-D-glucose and C-2 of \(\beta\)-D-fructose.
• [(C)] Incorrect — This describes lactose, which contains galactose and glucose.
• [(D)] Incorrect — This does not describe sucrose structure.

Hence, the correct answer is: \[ \boxed{\text{(B)}} \]