Class 12 Chemistry Biomolecules Notes

Class 12 Chemistry Biomolecules Notes

10.1 Carbohydrates

  • Definition: Organic compounds made of carbon, hydrogen, and oxygen (CH₂O)n
  • Classification:
    1. Monosaccharides – Simple sugars (e.g., glucose, fructose)
    2. Disaccharides – Two monosaccharides (e.g., sucrose, lactose)
    3. Polysaccharides – Many monosaccharides (e.g., starch, cellulose, glycogen)
  • Properties:
    • Soluble in water
    • Sweet taste (mono & disaccharides)
    • Form glycosidic bonds in polymers

10.2 Proteins

  • Definition: Polymers of amino acids linked by peptide bonds
  • Structure of Proteins:
    1. Primary: Sequence of amino acids
    2. Secondary: α-helix or β-sheet (hydrogen bonding)
    3. Tertiary: 3D folding
    4. Quaternary: Multiple polypeptide chains
  • Functions: Structural, enzymatic, transport, hormonal

10.3 Enzymes

  • Definition: Biological catalysts (mostly proteins)
  • Properties:
    • Highly specific for substrates
    • Operate under mild conditions
    • Can be denatured by heat or pH
  • Examples: Amylase, Protease, Lipase
  • Functions: Speed up biochemical reactions without being consumed

10.4 Vitamins

  • Definition: Organic compounds required in small amounts for normal metabolism
  • Classification:
    1. Fat-soluble: A, D, E, K
    2. Water-soluble: B-complex, C
  • Functions: Vision (A), bone health (D), antioxidant (E), blood clotting (K), coenzymes (B), antioxidant (C)

10.5 Nucleic Acids

  • Definition: Polymers of nucleotides (sugar + phosphate + nitrogenous base)
  • Types:
    • DNA (deoxyribonucleic acid) – genetic material
    • RNA (ribonucleic acid) – protein synthesis
  • Function: Storage, transmission, and expression of genetic information

10.6 Hormones

  • Definition: Chemical messengers secreted by endocrine glands
  • Types:
    1. Peptide hormones: Insulin, glucagon
    2. Steroid hormones: Testosterone, estrogen, cortisol
    3. Amine hormones: Adrenaline, thyroxine
  • Functions: Regulate metabolism, growth, reproduction, and homeostasis

📌 Important Exam Points

  • Carbohydrates: Monosaccharides are reducing sugars
  • Proteins: Structure determines function
  • Enzymes: Catalytic activity and specificity
  • Vitamins: Essential nutrients, deficiency causes disease
  • Nucleic acids: DNA stores genetic information, RNA helps in protein synthesis
  • Hormones: Endocrine signaling and regulation