Introduction
All living organisms are made up of chemical substances called biomolecules. These molecules are essential for:
- Structure of cells
- Energy production
- Metabolic activities
Biomolecules include both inorganic and organic compounds.
Types of Biomolecules
1. Inorganic Biomolecules
- Water
- Minerals
2. Organic Biomolecules
- Carbohydrates
- Proteins
- Lipids
- Nucleic acids
Biomacromolecules vs Micromolecules
| Type | Examples | Molecular Weight |
|---|---|---|
| Micromolecules | Amino acids, sugars | Low |
| Macromolecules | Proteins, DNA | High |
Carbohydrates
Definition
Carbohydrates are organic compounds made of carbon, hydrogen, and oxygen, usually in the ratio 1:2:1.
Classification
1. Monosaccharides
- Simplest sugars
- Cannot be hydrolyzed
Examples:
- Glucose
- Fructose
2. Disaccharides
- Two monosaccharides joined
Examples:
- Sucrose
- Lactose
3. Polysaccharides
- Long chains of sugars
Examples:
- Starch (plants)
- Glycogen (animals)
- Cellulose (plant cell wall)
Functions of Carbohydrates
- Energy source
- Structural role
- Storage of food
Proteins
Definition
Proteins are polymers of amino acids linked by peptide bonds.
Structure of Proteins
1. Primary Structure
- Sequence of amino acids
2. Secondary Structure
- α-helix or β-sheet
3. Tertiary Structure
- 3D folding
4. Quaternary Structure
- Multiple polypeptides
Functions of Proteins
- Enzymes
- Hormones
- Structural components
- Transport
Amino Acids
General Structure
NH2−CH(R)−COOH
Types of Amino Acids
- Essential
- Non-essential
Zwitterion
Amino acids exist as zwitterions in solution (both positive and negative charges).
Enzymes
Definition
Enzymes are biological catalysts that speed up biochemical reactions.
Properties
- Highly specific
- Work under optimal temperature and pH
- Reusable
Mechanism of Enzyme Action
- Enzyme + Substrate → Enzyme-Substrate complex → Product
Factors Affecting Enzyme Activity
- Temperature
- pH
- Substrate concentration
Lipids
Definition
Lipids are water-insoluble molecules made of fatty acids and glycerol.
Types
1. Simple Lipids
- Fats and oils
2. Compound Lipids
- Phospholipids
3. Derived Lipids
- Steroids
Functions
- Energy storage
- Structural role (cell membrane)
- Hormone formation
Nucleic Acids
Types
- DNA
- RNA
Structure of Nucleotide
- Nitrogenous base
- Pentose sugar
- Phosphate group
DNA vs RNA
| Feature | DNA | RNA |
|---|---|---|
| Sugar | Deoxyribose | Ribose |
| Bases | A, T, G, C | A, U, G, C |
| Structure | Double-stranded | Single-stranded |
Metabolism
Definition
Metabolism is the sum of all chemical reactions in the body.
Types
- Anabolism: Building up
- Catabolism: Breaking down
Important Concepts
1. ATP (Energy Currency)
- Stores and releases energy
2. Peptide Bond
- Bond between amino acids
3. Glycosidic Bond
- Bond in carbohydrates
4. Hydrogen Bond
- Stabilizes DNA and proteins
Important NEET & CBSE Points
- Carbohydrates = energy source
- Proteins = enzymes
- Lipids = membrane structure
- DNA = genetic material
- Enzymes = catalysts
Quick Revision Notes
- Biomolecules = life chemicals
- Carbs → energy
- Proteins → structure + enzymes
- Lipids → storage
- DNA → heredity
Frequently Asked Questions (FAQs)
Q1. What are biomolecules?
Chemical compounds present in living organisms.
Q2. What are enzymes?
Biological catalysts.
Q3. What is ATP?
Energy currency of cell.
Q4. What is a peptide bond?
Bond between amino acids.
Conclusion
Biomolecules form the chemical basis of life and are essential for structure, function, and metabolism of living organisms. This chapter is highly important for CBSE exams and NEET, especially for conceptual and application-based questions.