Chapter Summary

1. Elemental Analysis: Living organisms are composed of the same elements as non-living matter (C, H, O, N, etc.), but the relative abundance of Carbon and Hydrogen is higher in living organisms.

2. Biomicromolecules vs. Biomacromolecules:

  • Micromolecules (Acid Soluble): Molecular weight < 1000 Da (e.g., Amino acids, Sugars, Nucleotides).
  • Macromolecules (Acid Insoluble): Molecular weight > 10,000 Da (e.g., Proteins, Nucleic Acids, Polysaccharides).
  • The Lipid Exception: Lipids are micromolecules but are found in the macromolecule fraction because they form vesicles.

3. Proteins:

  • Polymers of amino acids linked by Peptide bonds.
  • Essential for structure (Collagen), catalysis (Enzymes), transport (GLUT-4), and defense (Antibodies).
  • Structure: Primary (Sequence), Secondary (α\alpha-helix, β\beta-sheet), Tertiary (3D folding, active site), Quaternary (Subunit assembly).

4. Nucleic Acids:

  • Polymers of nucleotides linked by Phosphodiester bonds.
  • DNA: Deoxyribose sugar, Thymine (A=T, G≡C), Double Helix.
  • RNA: Ribose sugar, Uracil instead of Thymine.

5. Polysaccharides:

  • Polymers of monosaccharides linked by Glycosidic bonds.
  • Storage: Starch (Plants, helical, blue with Iodine), Glycogen (Animals).
  • Structural: Cellulose (Plants, cell wall, no colour with Iodine), Chitin (Arthropods, N-acetyl glucosamine).

6. Metabolism:

  • Anabolic: Building up, consumes energy (Photosynthesis).
  • Catabolic: Breaking down, releases energy (Glycolysis).
  • Living State: A non-equilibrium steady-state to perform work.

7. Enzymes:

  • Biocatalysts that lower activation energy.
  • Function best at optimum temperature and pH.
  • Inhibition: Competitive (Malonate blocks Succinic dehydrogenase) vs. Non-competitive.
  • Co-factors: Prosthetic groups (Haem), Co-enzymes (NAD), Metal ions (Zinc).

High-Yield Exam Tips (NEET Focus)

1. Mnemonic for Enzyme Classes: Remember "OTHLIL" for the 6 classes of enzymes:

  • Oxidoreductases
  • Transferases
  • Hydrolases
  • Lyases
  • Isomerases
  • Ligases

2. Critical "Most Abundant" Facts:

  • Most abundant protein in Animal World: Collagen.
  • Most abundant protein in Biosphere: RuBisCO.

3. Bond Identification:

  • Peptide: Protein.
  • Glycosidic: Carbohydrate.
  • Phosphodiester: Nucleic Acid.
  • Ester: Lipids (Fatty acid + Glycerol).

4. Don't Get Confused:

  • Nucleoside = Sugar + Base (No Phosphate).
  • Nucleotide = Sugar + Base + Phosphate.
  • Inulin is a polymer of Fructose (Found in Dahlia roots).
  • Insulin is a protein hormone.

5. Secondary Metabolites Table: Memorize the NCERT table. A common question asks to match the category (e.g., Toxin) with the example (e.g., Ricin).