This category covers disaccharides — sugars formed when two monosaccharide units join through a glycosidic linkage. Questions look at familiar examples such as sucrose, maltose and lactose, how the linkage is formed and named, and how these sugars behave on hydrolysis. Useful for revising the carbohydrate section of biomolecules.
Maltose, made of two glucose units (each with 6 carbons), has a total of 12 carbon atoms (C₁2H₂2O₁1).
Ref: NCERT Class 12 Chemistry > Chapter 14: Biomolecules > Topic: Carbohydrates - Disaccharides and Glycosidic Linkage
Glucose is a common monosaccharide in lactose (with galactose) and sucrose (with fructose).
Ref: NCERT Class 12 Chemistry > Chapter 14: Biomolecules > Topic: Carbohydrates - Disaccharides and Glycosidic Linkage
Sucrose is a disaccharide made up of glucose and fructose, linked by an α-1,2-glycosidic bond.
Ref: NCERT Class 12 Chemistry > Chapter 14: Biomolecules > Topic: Carbohydrates - Disaccharides and Glycosidic Linkage
Galactose is an epimer of glucose, differing only at the C4 position in their open chain forms.
Ref: NCERT Class 12 Chemistry > Chapter 14: Biomolecules > Topic: Carbohydrates - Disaccharides and Glycosidic Linkage
Maltose, a reducing sugar with two glucose units, is fermented by yeast to produce ethanol and CO₂.
Ref: NCERT Class 12 Chemistry > Chapter 14: Biomolecules > Topic: Carbohydrates - Disaccharides and Glycosidic Linkage
Sucrose is a non-reducing sugar because it lacks a free anomeric carbon, so it does not react with Tollens’ reagent.
Ref: NCERT Class 12 Chemistry > Chapter 14: Biomolecules > Topic: Carbohydrates - Disaccharides and Glycosidic Linkage
Lactose is a reducing sugar because it has a free anomeric carbon on the glucose unit.
Ref: NCERT Class 12 Chemistry > Chapter 14: Biomolecules > Topic: Carbohydrates - Disaccharides and Glycosidic Linkage
Lactose is composed of galactose and glucose, linked by a β-1,4-glycosidic bond.
Ref: NCERT Class 12 Chemistry > Chapter 14: Biomolecules > Topic: Carbohydrates - Disaccharides and Glycosidic Linkage
Sucrose has a glycosidic bond between the anomeric carbon of glucose (C1) and fructose (C2), making it a non-reducing sugar.
Ref: NCERT Class 12 Chemistry > Chapter 14: Biomolecules > Topic: Carbohydrates - Disaccharides and Glycosidic Linkage
Lactose, a disaccharide, is the primary sugar found in milk.
Ref: NCERT Class 12 Chemistry > Chapter 14: Biomolecules > Topic: Carbohydrates - Disaccharides and Glycosidic Linkage
A non-reducing sugar has no free aldehyde or ketone group. Sucrose has its reducing groups involved in a glycosidic bond between glucose and fructose, making it non-reducing.
Ref: NCERT Class 12 Chemistry > Chapter 14: Biomolecules > Topic: Carbohydrates - Disaccharides and Glycosidic Linkage
Maltose is a disaccharide composed of two glucose units linked by an α-1,4-glycosidic bond.
Ref: NCERT Class 12 Chemistry > Chapter 14: Biomolecules > Topic: Carbohydrates - Disaccharides and Glycosidic Linkage
