Question

The correct statements about the following sugars X and Y are

• A. X is a reducing sugar and Y is a non-reducing sugar
• B. X is a non-reducing sugar and Y is a reducing sugar
• C. The glycosdic linkages in X and Y are $\alpha$ and $\beta$
• D. The glycosdic linkages in X and Y are $\beta$ and $\alpha$

Answer 1

Answer: (B), (C)

The glycosdic linkages in X and Y are $\alpha$ and $\beta$

In X, the glycocidic linkages between to anomeric $C$ atoms, while in Y, it is only with one anomeric carbon, the other one is free. X has the acetal linkage and Y has the hemiacetal linkage. As we know that the carbohydrates with hemiacetal linkage are reducing in nature and with acetal linkage are non-reducing in nature. Hence, it can be concluded that X is a non-reducing sugar and Y is a reducing sugar.
Also, X is the $\alpha$ anomer, and Y is the $\beta$ anomer of $D(+)$ Glucose. Therefore, the glycosidic linkages in X and Y are $\alpha$ and $\beta$ respectively.