Bihar Board - Class 11 biology - Chapter 9: Biomolecules Handwritten Notes

Biomolecules are the chemical compounds that make up living organisms and are essential for life processes. These include carbohydrates, proteins, lipids, nucleic acids, and other small molecules like vitamins and minerals. This chapter explores the structure, classification, and functions of these biomolecules, highlighting their role in maintaining life and facilitating biological reactions.

Key Points

1. Types of Biomolecules

   • Carbohydrates:
     • Composed of carbon, hydrogen, and oxygen (CH₂O)n.
     • Provide energy and structural support.
     • Types:
       • Monosaccharides: Glucose, fructose.
       • Disaccharides: Sucrose, lactose.
       • Polysaccharides: Starch, glycogen, cellulose.
   • Proteins:
     • Made of amino acids linked by peptide bonds.
     • Functions: Enzymes, hormones, structural components, transport.
     • Levels of structure: Primary, secondary, tertiary, and quaternary.
   • Lipids:
     • Non-polar molecules composed of fatty acids and glycerol.
     • Types: Fats, oils, phospholipids, steroids.
     • Functions: Energy storage, membrane structure, signaling molecules.
   • Nucleic Acids:
     • DNA and RNA; made of nucleotides (sugar, phosphate, nitrogenous base).
     • Functions: Genetic information storage (DNA), protein synthesis (RNA).

2. Enzymes

   • Biological catalysts that speed up chemical reactions.
   • Highly specific to substrates and function under optimal pH and temperature.
   • Types: Oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases.
   • Examples: Amylase, pepsin, DNA polymerase.

3. Metabolic Pathways

   • Biochemical reactions in the cell are organized into pathways:
     • Anabolism: Synthesis of complex molecules (e.g., photosynthesis).
     • Catabolism: Breakdown of complex molecules (e.g., respiration).
   • ATP (Adenosine Triphosphate) acts as the energy currency in these pathways.

4. Water and Its Role

   • Acts as a solvent, medium for chemical reactions, and helps in temperature regulation and transportation of nutrients.

5. Vitamins and Minerals

   • Micronutrients essential for specific biochemical reactions and structural roles.
   • Examples:
     • Vitamins: Vitamin A, B-complex, C, D, E, K.
     • Minerals: Calcium, iron, magnesium, potassium.

6. Tests for Biomolecules

   • Biochemical tests used to identify biomolecules:
     • Benedict's test: Detects reducing sugars.
     • Biuret test: Identifies proteins.
     • Iodine test: Detects starch.
     • Sudan III test: Identifies lipids.

7. Significance of Biomolecules

   • Serve as building blocks of cells and tissues.
   • Participate in energy production and metabolic regulation.
   • Essential for growth, repair, and reproduction.

Conclusion

Biomolecules are the foundation of all life processes, forming the structural and functional components of living organisms. Understanding their structure and role provides insights into the biochemical basis of life, making biomolecules a cornerstone of biology and biochemistry.