JEE MainChemistryBiomolecules
Which of the following statements correctly describes the structure and chemical nature of lactose?
Options
- AIt is composed of -D-galactose and -D-glucose linked between C₁ of galactose and C₄ of glucose, and it is a re
- BIt is composed of -D-glucose and -D-fructose linked between C₁ of glucose and C₂ of fructose, and it is a non-
- CIt is composed of two -D-glucose units linked between C₁ and C₄ , and it is a reducing sugar.
- DIt is composed of -D-galactose and -D-glucose linked between C₁ of galactose and C₄ of glucose, and it is a no
Correct answer
A. It is composed of -D-galactose and -D-glucose linked between C₁ of galactose and C₄ of glucose, and it is a re
Step-by-step solution
Lactose (milk sugar) is a naturally occurring disaccharide composed of -D-galactose and -D-glucose. The glycosidic linkage is formed between C₁ of the galactose unit and C₄ of the glucose unit. Because the anomeric carbon ( C₁ ) of the glucose unit is not involved in the glycosidic linkage and remains free to form a hemiacetal group in aqueous solution, lactose acts as a reducing sugar. Answer: It is composed of -D-galactose and -D-glucose linked between C₁ of galactose and C₄ of glucose, and it is a reducing sugar