Question

When forming the disaccharide maltose from glucose monosaccharides:

A. Two anomeric carbons react to form an acetal group.
B. Water is eliminated and a hemiacetal is converted to an acetal.
C. An acetal group is converted into a hemiacetal.
D. The resulting disaccharide is no longer a reducing sugar.

Answer 1

Water is eliminated, and a hemiacetal is converted into an acetal when forming maltose from glucose. This forms an α-1,4-glycosidic linkage, and maltose remains a reducing sugar due to the free anomeric carbon.

Step-by-step explanation:

When forming the disaccharide maltose from glucose monosaccharides, the correct statement is: B .Water is eliminated, and a hemiacetal is converted to an acetal . During the dehydration synthesis of maltose from two glucose molecules, a water molecule is eliminated. This process involves the conversion of a cyclic hemiacetal group on one glucose into an acetal as it forms a glycosidic linkage, with the hydroxyl group of the other glucose molecule. Specifically, theα-1,4-glycosidic linkage is formed between the anomeric carbon of the first glucose (in its cyclic hemiacetal form) and the fourth carbon of the second glucose. Maltose is considered a reducing sugar because it has a free anomeric carbon that can revert to the aldehyde form and react with common oxidizing agents.