Carbohydrates: Introduction

This lesson covers:

  1. The elements that carbohydrates contain
  2. The role of carbohydrates in living organisms
  3. The different types of carbohydrates

What are carbohydrates?

Carbohydrates are biological molecules that contain the elements carbon (C), hydrogen (H), and oxygen (O). 


  1. 'Carbo' - Contains the element carbon.
  2. 'Hydrate' - Contains hydrogen and oxygen atoms in a ratio of 2:1 like water (H2O).


The general formula for a carbohydrate is Cx(H2O)y.

Roles of carbohydrates

Functions of carbohydrates in living organisms:

  1. Energy supply for cells - This is the main role of carbohydrates. 
  2. Energy storage - Sugars can be stored as complex carbohydrates (e.g. starch or glycogen). 
  3. Structural components - Cellulose and chitin are used in cell walls. 
  4. Cellular recognition - Glycoproteins help cells identify each other and communicate. 
  5. Building blocks for biological molecules - Deoxyribose and ribose can be used to make nucleic acids.

Types of carbohydrates

There are three types of carbohydrates: monosaccharides, disaccharides, and polysaccharides. 

Table showing types of carbohydrates including monosaccharides, disaccharides, and polysaccharides with examples and functions.