Biomolecules Question 81
81. Which of the following is a reducing sugar?
(a) galactose
(b) gluconic acid
(c) $\beta$-methyl galactoside
(d) sucrose
Show Answer
Answer : a
Hints & Solutions
(a) Reducing sugar is any sugar that has an aldehyde group or is capable of forming one, in solution through isomerisation. Reducing monosaccharides include glucose, fructose, glyceraldehyde and galactose. Many disaccharides, like lactose and maltose also have a reducing form, as one of the two units may have an open- chain form with an aldehyde group. However, sucrose and trehalose, in which the anomeric carbons of the two units are linked together, are non reducing disaccharides since neither of the rings is capable of opening.
