Disaccharides and Polysaccharides
Formation, structure, and examples of complex carbohydrates such as sucrose, lactose, maltose, starch, cellulose, and glycogen.
What is Disaccharides and Polysaccharides?
A type of covalent bond that links a carbohydrate molecule to another group, formed by the dehydration reaction between two hydroxyl groups.
Key points
- Understand the formation of disaccharides and polysaccharides.
- Identify the types of glycosidic linkages.
- Differentiate between common disaccharides and polysaccharides.
- Explain the structure and function of starch, cellulose, and glycogen.
Common exam trap
Confusing the types of glycosidic bonds (α vs. β) and their implications.
Definitions
- Term
Glycosidic bond
- Meaning
A type of covalent bond that links a carbohydrate molecule to another group, formed by the dehydration reaction between two hydroxyl groups.
- Term
Reducing sugar
- Meaning
A sugar that has a free aldehyde or ketone group, capable of acting as a reducing agent.
- Term
Non-reducing sugar
- Meaning
A sugar that lacks a free aldehyde or ketone group, and therefore cannot act as a reducing agent.
Learning objectives
Understand the formation of disaccharides and polysaccharides.
Identify the types of glycosidic linkages.
Differentiate between common disaccharides and polysaccharides.
Explain the structure and function of starch, cellulose, and glycogen.
Prerequisites
Monosaccharides (structure and properties)
Basic organic chemistry concepts (functional groups, dehydration synthesis)
Common mistakes
Confusing the types of glycosidic bonds (α vs. β) and their implications.
Incorrectly identifying the constituent monosaccharides in disaccharides.
Not distinguishing between the structural and storage roles of different polysaccharides.
Assuming all polysaccharides are digestible by humans.
Keywords
Disaccharide
Polysaccharide
Glycosidic bond
Sucrose
Lactose
Maltose
Starch
Cellulose
Glycogen
Reducing sugar
Non-reducing sugar
Practice preview
Which of the following is a reducing sugar?…
easy
The glycosidic bond in sucrose is formed between:…
easy
Cellulose and glycogen are both polymers of glucose. However, they differ significantly in their:…
medium