Introduction to Biomolecules

Biomolecules are organic and inorganic compounds essential for life. They form the structural and functional basis of cells and tissues. In NEET, understanding structure, classification, and properties of biomolecules is crucial as it connects chemistry with biology.

Main classes include:

• Carbohydrates – Energy storage and structural molecules.

• Proteins and Amino Acids – Building blocks of life.

• Lipids – Fats, oils, and membranes.

• Nucleic Acids – DNA and RNA, carriers of genetic information.

• Vitamins and Hormones – Biologically active molecules regulating metabolic processes.

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Carbohydrates

Carbohydrates are polyhydroxy aldehydes or ketones, classified as:

1. Monosaccharides – Simple sugars (glucose, fructose, galactose).

2. Disaccharides – Two monosaccharides linked by glycosidic bond (sucrose, lactose).

3. Polysaccharides – Many monosaccharides (starch, glycogen, cellulose, chitin).

Physical Properties:

• Sweet taste, soluble in water, optically active (except diastereomers).

Chemical Properties:

• Reducing and non-reducing sugars – Determined by free aldehyde/ketone groups.

• Oxidation – Forms acids.

• Esterification and Glycosidic bond formation – Important in polysaccharide synthesis.

NEET often focuses on classification, functional groups, and reactions of sugars.

Proteins and Amino Acids

Proteins are polymers of amino acids connected via peptide bonds.

Amino Acids:

• Contain amino (-NH2) and carboxyl (-COOH) groups.

• Classified as essential or non-essential.

Protein Structure:

1. Primary – Sequence of amino acids.

2. Secondary – α-helix, β-sheet.

3. Tertiary – 3D folding.

4. Quaternary – Multiple polypeptide chains.

Chemical Properties:

• Biuret test – For peptide bonds.

• Denaturation – Heat, pH, or chemicals affect structure but not primary sequence.

NEET focuses on amino acid classification, protein structure, and tests.

Lipids

Lipids are hydrophobic biomolecules, mainly fats, oils, and phospholipids.

Types:

• Simple lipids – Fats and oils (glycerol + fatty acids).

• Compound lipids – Phospholipids, glycolipids.

• Derived lipids – Steroids, waxes, terpenes.

Functions:

• Energy storage, membrane structure, insulation, and signaling (steroid hormones).

Chemical Properties:

• Saponification – Fats react with alkali to form soap.

• Unsaturated lipids can be hydrogenated.

NEET questions often ask about structure, classification, and function of lipids.

Nucleic Acids

Nucleic acids (DNA and RNA) are polymers of nucleotides.

Components of Nucleotides:

1. Nitrogenous base (purine or pyrimidine)

2. Pentose sugar (deoxyribose or ribose)

3. Phosphate group

DNA vs RNA:

Functions:

• DNA stores genetic information.

• RNA transfers genetic information and catalyzes protein synthesis (mRNA, tRNA, rRNA).

NEET focuses on structure, base pairing, and types of nucleic acids.

Vitamins

Vitamins are organic compounds required in small amounts for metabolism.

Classification:

1. Fat-soluble: A, D, E, K – Stored in liver and fat.

2. Water-soluble: B-complex, C – Not stored; excess excreted.

Functions:

• Vitamin A – Vision

• Vitamin D – Calcium metabolism

• Vitamin E – Antioxidant

• Vitamin K – Blood clotting

• Vitamin C – Collagen synthesis

NEET often tests functions, deficiency symptoms, and solubility.

Hormones

Hormones are chemical messengers regulating physiological processes.

Examples:

• Peptide hormones – Insulin, glucagon

• Steroid hormones – Testosterone, estrogen, cortisol

• Amine hormones – Adrenaline, thyroxine

Functions:

• Growth, metabolism, reproduction, and stress response.

NEET focuses on types, sources, and biological functions.

Applications and Importance

1. Carbohydrates: Energy supply and structural role.

2. Proteins: Enzymes, structural components, transport (hemoglobin).

3. Lipids: Membrane structure, energy storage, signaling molecules.

4. Nucleic Acids: Heredity, protein synthesis, and genetic engineering.

5. Vitamins & Hormones: Regulation of metabolism, growth, and reproduction.

Connecting structure with function is a high-yield NEET strategy.

Tips for NEET Students

1. Focus on classification, structure, and functions of each biomolecule.

2. Use tables and flowcharts to memorize comparisons and properties.

3. Remember functional group reactions where relevant (e.g., carbohydrates, amino acids).

4. Revise deficiency symptoms and biological importance of vitamins and hormones.

5. Practice MCQs connecting chemistry with biological applications.

Conclusion

Biomolecules are critical topics in NEET Chemistry, bridging organic chemistry with biology. Mastering carbohydrates, proteins, lipids, nucleic acids, vitamins, and hormones ensures students can confidently tackle mechanism-based, conceptual, and application-based NEET questions.

At StudentBro.in, we provide concise, exam-focused notes for NEET 2026 aspirants, enabling efficient revision, strong conceptual clarity, and improved exam performance.