Which one of the following sets of monosaccharides forms sucrose ?

Options

A. `alpha`-D-glucopyranose and `beta`-D-fructofuranose
B. `beta`-D-glycopyranose and `alpha`-D-fructofuranose
C. `alpha`-D-glucopyranose and `beta`-D-fructopyranose
D. `alpha`-D-galactopyranose and `alpha`-D-glucopyranose

Answer

A

Explanation

Sucrose is composed of `alpha`-D glucopyranose and `beta`-D-fructofuranose units which are joined by `alpha,beta`-glucosidic linkage between C-1 of the glucose unit and C-2 of the fructose unit.