Overview of Carbohydrates: Structure, Types, and Functions

Carbohydrates

Introduction to Carbohydrates

Carbohydrates are essential biomolecules composed of carbon, hydrogen, and oxygen. They serve as a primary energy source for living organisms and play structural and communicative roles in cells.

• General Formula: Most carbohydrates have the empirical formula (CH2O)n.

• Elements: Carbon (C), Hydrogen (H), Oxygen (O)

Classification of Carbohydrates

• Monosaccharides: Simple sugars that cannot be hydrolyzed into smaller carbohydrates. Examples include glucose and fructose.

• Disaccharides: Composed of two monosaccharide units. Examples: sucrose (glucose + fructose), lactose (glucose + galactose).

• Oligosaccharides: Short chains of 3–10 monosaccharide units.

• Polysaccharides: Long chains of monosaccharide units. Examples: starch, glycogen, cellulose.

Examples of Carbohydrates

• Glucose: A primary energy source for cells.

• Sucrose: Table sugar, a disaccharide of glucose and fructose.

• Lactose: Milk sugar, a disaccharide of glucose and galactose.

• Starch: Storage polysaccharide in plants.

• Glycogen: Storage polysaccharide in animals.

• Cellulose: Structural polysaccharide in plant cell walls.

Functions of Carbohydrates

• Energy: Carbohydrates are the main source of energy for most organisms. Glucose is metabolized to produce ATP.

• Structural: Cellulose in plants and chitin in arthropods provide structural support.

• Communication: Glycoproteins and glycolipids on cell surfaces are involved in cell recognition and signaling.

• Localization: Carbohydrates are found in various cellular locations, including the cell membrane and cytoplasm.

Important Concepts and Terms

• Monomer: The simplest unit of a carbohydrate (e.g., glucose).

• Polymer: Large molecules made by linking many monomers (e.g., starch, glycogen).

• Hydrolysis: The chemical breakdown of a compound due to reaction with water, such as the breakdown of disaccharides into monosaccharides.

Summary Table: Types of Carbohydrates

Type	Number of Sugar Units	Examples	Main Function
Monosaccharide	1	Glucose, Fructose	Energy
Disaccharide	2	Sucrose, Lactose	Energy
Oligosaccharide	3–10	Raffinose	Cell recognition
Polysaccharide	Many	Starch, Glycogen, Cellulose	Energy storage, Structure

Key Equations

• General formula for monosaccharides:

$C_n(H_2O)_n$

• Example: Hydrolysis of Sucrose

$\text{Sucrose} + H_2O \rightarrow \text{Glucose} + \text{Fructose}$

Additional info: Some terms and examples were inferred and expanded for academic completeness based on standard biochemistry curriculum.