Question

Which of the glycosidic linkage between galactose and glucose is present in lactose ?

• A. C-1 of galactose and C-4 of glucose
• B. C-1 of galactose and C-6 of glucose
• C. C-1 of glucose and C-4 of galactose
• D. C-1 of glucose and C-6 of galactose

Hint:

In Lactose, the glucose unit has a free anomeric carbon at C-1, making it a {reducing sugar}.

Answer 1

The Correct Option is A

Step 1: Lactose is a disaccharide composed of $\beta$-D-galactose and $\beta$-D-glucose.
Step 2: The linkage is formed between the anomeric carbon (C-1) of the galactose unit and the C-4 hydroxyl group of the glucose unit.
Step 3: This is specifically a $\beta$-1,4-glycosidic linkage.