Biomacromolecules Class 11 Notes (Proteins, Polysaccharides, Nucleic Acids) | NCERT + NEET

 Biomacromolecules

Inside every living cell, thousands of organic compounds are present. Some of these molecules are very small and simple, while others are extremely large and complex.

The large, high molecular weight biological molecules found in living organisms are called biomacromolecules.

These molecules are essential for structure, metabolism, growth, storage, and genetic control in organisms.

🔬 What are Biomacromolecules?

Biomacromolecules are large organic molecules formed by the polymerisation of smaller units called monomers.

They usually have molecular weights greater than 1000 Daltons.

Examples:

• Proteins

• Polysaccharides

• Nucleic acids

These molecules are generally insoluble in acid and form the acid-insoluble fraction of cells.

⚡ Characteristics of Biomacromolecules:

Important features of biomacromolecules:

• Very large molecular size

• High molecular weight

• Usually polymeric in nature

• Mostly insoluble in water

• Formed by joining many monomers

• Essential for cellular activities

🧪 Types of Biomacromolecules:

1️⃣ Proteins:

Proteins are polymers of amino acids linked together by peptide bonds.

Functions of proteins:

• Enzymatic activity

• Structural support

• Transport of substances

• Hormonal regulation

• Immune defense

Examples:

• Hemoglobin

• Insulin

• Keratin

• Collagen

2️⃣ Polysaccharides:

Polysaccharides are complex carbohydrates formed by many monosaccharide units.

Functions:

• Energy storage

• Structural support

Examples:

• Starch

• Glycogen

• Cellulose

• Chitin

Cellulose forms the plant cell wall, while chitin is present in fungal cell walls.

3️⃣ Nucleic Acids:

Nucleic acids are polymers of nucleotides.

Types:

• DNA (Deoxyribonucleic Acid)

• RNA (Ribonucleic Acid)

Functions:

• Store genetic information

• Control protein synthesis

• Transfer hereditary characters

📊 Difference Between Micromolecules and Macromolecules:

Feature	Micromolecules	Macromolecules
Size	Small	Large
Molecular Weight	Low	High
Solubility	Soluble	Mostly insoluble
Examples	Amino acids, sugars	Proteins, DNA

🧠 Important NEET Points: Biomacromolecules belong to the acid-insoluble fraction. Proteins are polymers of amino acids. Nucleic acids are polymers of nucleotides. Polysaccharides are polymers of monosaccharides. Molecular weight is measured in Daltons. 📌 NCERT Highlight: Living organisms contain both micromolecules and macromolecules. Macromolecules mainly perform structural and functional roles in cells. ❓ Practice MCQs: Q1. Biomacromolecules are generally: A) Acid soluble B) Acid insoluble C) Volatile D) Inorganic ✔ Answer: B Q2. Proteins are polymers of: A) Fatty acids B) Monosaccharides C) Amino acids D) Nucleotides ✔ Answer: C Q3. Which of the following is a polysaccharide? A) Glucose B) Fructose C) Glycogen D) Glycerol ✔ Answer: C Q4. DNA is made up of: A) Amino acids B) Nucleotides C) Fatty acids D) Sugars ✔ Answer: B 🌟 Conclusion: Biomacromolecules are large and complex biological molecules essential for life. Proteins, polysaccharides, and nucleic acids perform important structural, metabolic, and genetic functions in living organisms. Understanding biomacromolecules is extremely important for NEET preparation because many conceptual and MCQ-based questions are asked from this topic.