Biomolecules – NEET Chemistry Class 12

Biomolecules are organic and inorganic compounds present in living organisms essential for life. This chapter is crucial for NEET as it includes carbohydrates, proteins, amino acids, nucleic acids, lipids, and vitamins, which are frequently asked in both theory and application-based questions.

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Introduction to Biomolecules

• Definition: Molecules that are vital for structural and functional roles in organisms.

• Types: Carbohydrates, Proteins, Lipids, Nucleic acids, Vitamins, and Hormones.

• Importance: Biomolecules are central to understanding metabolism, enzymatic reactions, and biochemical pathways.

Carbohydrates

• Definition: Polyhydroxy aldehydes or ketones or compounds that yield them on hydrolysis.

• Classification:

  • Monosaccharides (e.g., Glucose, Fructose)

  • Disaccharides (e.g., Sucrose, Lactose)

  • Polysaccharides (e.g., Starch, Glycogen, Cellulose)

• Functions: Energy storage (starch, glycogen), structural roles (cellulose, chitin).

• NEET Focus: Reducing vs non-reducing sugars, ring structures, and glycosidic bonds.

Proteins and Amino Acids

• Amino Acids: Building blocks of proteins with general formula H₂N–CHR–COOH.

  • Classified as essential or non-essential

  • Zwitterions: Dipolar ions present in aqueous solutions

• Proteins: Polymers of amino acids linked by peptide bonds

  • Primary, secondary, tertiary, and quaternary structures

• Functions: Enzymes, structural proteins, transport proteins, hormones

• NEET Focus: Peptide linkage, denaturation, types of proteins

Lipids

• Definition: Hydrophobic molecules including fats, oils, phospholipids, and steroids.

• Functions: Energy storage, cell membrane structure, insulation, and signaling

• NEET Focus: Saponification, triglycerides, and phospholipids in membranes

Nucleic Acids

• DNA and RNA: Polymers of nucleotides (phosphate + sugar + nitrogenous base)

• Functions: Storage and transmission of genetic information

• NEET Focus: Complementary base pairing, structure of nucleotides, types of RNA

Vitamins

• Definition: Organic compounds required in trace amounts for metabolism

• Fat-soluble: A, D, E, K

• Water-soluble: B-complex, C

• Functions: Coenzymes, antioxidants, bone health, vision, and immunity

• NEET Focus: Deficiency diseases and functions

Enzymes

• Definition: Biological catalysts that increase reaction rates

• Properties: Specificity, temperature and pH sensitivity, coenzymes/cofactors

• NEET Focus: Mechanism, activation energy, and examples like amylase, lipase

Importance for NEET Preparation

• Biomolecules are frequently asked in theoretical, diagram-based, and application-oriented questions.

• Understanding structure-function relationships is crucial for solving NEET questions.

• Topics like carbohydrate tests, amino acid properties, enzyme mechanisms, and vitamin functions are high-yield.

Previous Year NEET Questions – Insights

• Identifying monosaccharides, disaccharides, and polysaccharides

• Protein structure and peptide bond reactions

• Functions of lipids and nucleic acids in living organisms

• Deficiency diseases due to lack of vitamins

• Enzyme activity, specificity, and cofactor roles

Study Tips for Students

1. Memorize Structures and Functions – Carbohydrates, proteins, lipids, nucleic acids, vitamins

2. Practice Reaction Mechanisms – Peptide bond formation, saponification

3. Understand Functional Roles – Energy storage, structural roles, enzymatic functions

4. Refer NCERT Examples – NEET often follows NCERT diagrams and reactions

5. Solve Previous Year Questions – Reinforces understanding and exam pattern

Conclusion

Mastering Biomolecules is essential for NEET success. It allows students to understand biological processes, answer structure-function questions, and tackle application-based problems confidently. A strong command of this chapter ensures high scoring potential in Class 12 organic chemistry and biochemistry-based questions.