Question

Which one of the following sets of monosaccharides forms sucrose?

• A. \( \alpha \)-D-galactopyranose and \( \alpha \)-D-glucopyranose
• B. \( \alpha \)-D-glucopyranose and \( \beta \)-D-fructofuranose
• C. \( \beta \)-D-glucopyranose and \( \alpha \)-D-fructofuranose
• D. \( \alpha \)-D-glucopyranose and \( \beta \)-D-fructopyranose

Hint:

Sucrose is formed from an \( \alpha \)-D-glucopyranose and a \( \beta \)-D-fructofuranose through a condensation reaction, creating a glycosidic bond between the two monosaccharides.

Answer 1

The Correct Option is B

Sucrose is a disaccharide composed of two monosaccharides: glucose and fructose. Specifically, sucrose is formed when an \( \alpha \)-D-glucopyranose molecule and a \( \beta \)-D-fructofuranose molecule undergo condensation, resulting in the formation of a glycosidic bond between the two sugar units. This disaccharide is commonly known as table sugar. - Option (a) is incorrect because galactose does not participate in the formation of sucrose.
- Option (c) is incorrect because it involves a \( \beta \)-D-glucopyranose unit, but sucrose is made from an \( \alpha \)-D-glucopyranose unit.
- Option (d) is incorrect because it involves a \( \beta \)-D-fructopyranose, but sucrose involves a \( \beta \)-D-fructofuranose. Therefore, the correct answer is option (b).