Oligosaccharides: Lactose and Maltose
Structures of lactose and maltose (reducing sugars), their constituent monosaccharides, and hydrolysis.
What is Oligosaccharides: Lactose and Maltose?
A carbohydrate formed by the glycosidic linkage of two monosaccharide units.
Key points
- Identify lactose and maltose as disaccharides.
- Describe the constituent monosaccharides of lactose and maltose.
- Explain the type of glycosidic linkage in lactose and maltose.
- Understand why lactose and maltose are reducing sugars.
Common exam trap
Confusing the constituent monosaccharides of lactose and maltose.
Definitions
- Term
Disaccharide
- Meaning
A carbohydrate formed by the glycosidic linkage of two monosaccharide units.
- Term
Glycosidic bond
- Meaning
A type of covalent bond that links a carbohydrate molecule to another group, typically another carbohydrate or an alcohol. In disaccharides, it links two monosaccharides.
- Term
Reducing sugar
- Meaning
A sugar that has a free aldehyde or ketone group, or can isomerize to a form with such a group, which can reduce oxidizing agents.
- Term
Hydrolysis
- Meaning
A chemical reaction in which a molecule of water is used to break down a compound. In carbohydrates, it breaks glycosidic bonds.
Learning objectives
Identify lactose and maltose as disaccharides.
Describe the constituent monosaccharides of lactose and maltose.
Explain the type of glycosidic linkage in lactose and maltose.
Understand why lactose and maltose are reducing sugars.
Describe the products of hydrolysis for lactose and maltose.
Prerequisites
Monosaccharides (Glucose, Galactose)
Glycosidic bond formation
Structure of carbohydrates
Reducing and non-reducing sugars
Common mistakes
Confusing the constituent monosaccharides of lactose and maltose.
Forgetting the type of glycosidic linkage (α or β) and the positions involved (1,4).
Not understanding why they are classified as reducing sugars.
Confusing oligosaccharides with polysaccharides.
Keywords
Oligosaccharide
Disaccharide
Lactose
Maltose
Milk sugar
Malt sugar
Glycosidic bond
Reducing sugar
Hydrolysis
Galactose
Glucose
α-1,4 linkage
β-1,4 linkage
Practice preview
Maltose, also known as malt sugar, is a disaccharide formed by the glycosidic linkage of which two monosaccharide units?…
easy
Hydrolysis of lactose yields:…
medium
Which of the following statements about lactose and maltose is INCORRECT?…
hard