Lesson: Biomolecules – The Building Blocks of Life

Introduction to Biomolecules

Biomolecules, also known as biological molecules, are substances produced by living organisms. These molecules are essential for growth, energy storage, metabolism, and cell structure. The four major types of biomolecules are:

  1. Carbohydrates – Provide energy.
  2. Lipids (Fats and Oils) – Store energy and make cell membranes.
  3. Proteins – Build body structures and speed up chemical reactions.
  4. Nucleic Acids (DNA & RNA) – Carry genetic information.

Since biomolecules are large molecules, they are also called macromolecules.

Role of Biomolecules in Organisms

Biomolecules play a crucial role in both the structure and functioning of living organisms.

  • 93% of an organism’s dry weight consists of biomolecules.
  • The remaining 7% includes vitamins, minerals, salts, and other inorganic substances.
  • All chemical reactions happening in the body are called metabolism.

Types of Metabolism

Metabolism has two main types:

  1. Anabolism – The process in which smaller molecules combine to form larger molecules.
    • Example: Plants making starch from glucose.
    • Energy is used in anabolism.
  2. Catabolism – The process in which larger molecules break down into simpler molecules.
    • Example: Digestion of food where proteins break into amino acids.
    • Energy is released in catabolism.

Carbohydrates – The Energy Source

The word carbohydrate means “hydrated carbon” because it contains carbon (C), hydrogen (H), and oxygen (O) in a 2:1 ratio, just like water (H₂O).

Carbohydrates are also called “saccharides”, which means sugars. Their general formula is (CH₂O)ₙ, where “n” is the number of carbon atoms.

Types of Carbohydrates

Carbohydrates are divided into three main groups based on their complexity:

1. Monosaccharides (Simple Sugars)

  • Definition: Monosaccharides are the simplest form of carbohydrates made of a single sugar molecule.
  • Properties:
    • Easily dissolve in water.
    • Have a sweet taste.
    • Contain 3 to 7 carbon atoms.
  • Common Examples:
    • Pentoses (5-carbon sugars):
      • Ribose (C₅H₁₀O₅) – Found in RNA.
      • Deoxyribose (C₅H₁₀O₄) – Found in DNA.
    • Hexoses (6-carbon sugars):
      • Glucose (C₆H₁₂O₆) – Main source of energy for the body.
      • Fructose (C₆H₁₂O₆) – Found in fruits.
      • Galactose (C₆H₁₂O₆) – Found in milk.

📌 Example in Daily Life: Glucose is found in honey and fruits, and the body uses it for instant energy.

2. Disaccharides (Double Sugars)

  • Definition: Disaccharides are formed when two monosaccharides join together.
  • Properties:
    • Less soluble in water than monosaccharides.
    • Less sweet than monosaccharides.
  • Common Examples:
    • Sucrose (Table Sugar) = Glucose + Fructose
    • Maltose (Malt Sugar) = Glucose + Glucose

📌 Example in Daily Life:

  • Sucrose is the common sugar we use in tea.
  • Maltose is found in malted cereals and grains.

Conclusion

  • Biomolecules are essential for life and include carbohydrates, lipids, proteins, and nucleic acids.
  • Carbohydrates are the primary source of energy and are classified into monosaccharides, disaccharides, and polysaccharides.
  • Monosaccharides are simple sugars like glucose, fructose, and galactose.
  • Disaccharides are made by joining two simple sugars, such as sucrose and maltose.

In the next lesson, we will explore polysaccharides and their role in energy storage and structural support! 🚀