Introduction to Carbohydrates
Basic definition, general formula, and classification into monosaccharides, disaccharides, and polysaccharides.
What is Introduction to Carbohydrates?
An organic compound consisting of carbon, hydrogen, and oxygen, typically with a hydrogen–oxygen atom ratio of 2:1, serving as a major source of energy.
Key formula / rule: General Formula of Carbohydrates
Key points
- Define carbohydrates and state their general formula.
- Explain the classification of carbohydrates into monosaccharides, disaccharides, and polysaccharides.
- Identify examples of each class of carbohydrate.
- Understand the basic functional roles of carbohydrates.
Common exam trap
Confusing the general formula (CH2O)n with all carbohydrates, as some exceptions exist (e.g., deoxyribose).
Definitions
- Term
Carbohydrate
- Meaning
An organic compound consisting of carbon, hydrogen, and oxygen, typically with a hydrogen–oxygen atom ratio of 2:1, serving as a major source of energy.
- Term
Monosaccharide
- Meaning
The simplest form of carbohydrate, a single sugar unit, which cannot be hydrolyzed into simpler carbohydrates (e.g., glucose, fructose).
- Term
Disaccharide
- Meaning
A carbohydrate formed by the glycosidic linkage of two monosaccharide units (e.g., sucrose, lactose).
- Term
Polysaccharide
- Meaning
A complex carbohydrate composed of a long chain of monosaccharide units linked by glycosidic bonds (e.g., starch, cellulose).
- Term
Glycosidic bond
- Meaning
A type of covalent bond that links a carbohydrate molecule to another group, typically another carbohydrate.
Learning objectives
Define carbohydrates and state their general formula.
Explain the classification of carbohydrates into monosaccharides, disaccharides, and polysaccharides.
Identify examples of each class of carbohydrate.
Understand the basic functional roles of carbohydrates.
Formulae
- Name
General Formula of Carbohydrates
- Note
Represents the ratio of hydrogen to oxygen atoms as 2:1, similar to water. Note that some exceptions exist.
- Expression
(CH2O)n
Prerequisites
Basic organic chemistry concepts (elements, compounds).
Understanding of chemical formulas and nomenclature.
Common mistakes
Confusing the general formula (CH2O)n with all carbohydrates, as some exceptions exist (e.g., deoxyribose).
Not understanding the difference between structural and storage polysaccharides.
Misidentifying the constituent monosaccharides in disaccharides.
Keywords
Carbohydrate
Saccharide
Monosaccharide
Disaccharide
Polysaccharide
Glucose
Fructose
Sucrose
Starch
Cellulose
Energy
Biomolecule
Glycosidic bond
Practice preview
Which of the following is a common example of a polysaccharide used for energy storage in plants?…
medium
Carbohydrates are classified into which of the following categories based on their size?…
easy
Which of the following is an example of a monosaccharide?…
easy