Question

Lactose is a disaccharide formed between C-1 of ....... and C-4 of ..........

• A. Galactose, Glucose
• B. Fructose, Glucose
• C. Glucose, Fructose
• D. Glucose, Galactose
• E.

Hint:

Lactose = Galactose + Glucose, joined by a β-1,4 glycosidic bond.

Answer 1

The Correct Option is A

Step 1: Definition of Lactose.
Lactose is a disaccharide. It consists of the monosaccharides galactose and glucose.
The bond is a glycosidic bond, connecting C-1 of galactose to C-4 of glucose.
Step 2: Evaluation of Options.
- (1) Galactose, Glucose: Correct. Lactose is composed of galactose and glucose.
- (2) Fructose, Glucose: Incorrect. Fructose is not a component of lactose.
- (3) Glucose, Fructose: Incorrect. Lactose is not formed from glucose and fructose.
- (4) Glucose, Galactose: Incorrect. The specific linkage involves C-1 of galactose and C-4 of glucose, making this order incorrect.
Step 3: Final Determination.
Consequently, lactose is formed via the bond between C-1 of galactose and C-4 of glucose.