DNA Structure and Base Pairing

  • DNA (Deoxyribonucleic acid): Molecule of heredity, genetic blueprint for life.
  • Nucleotide Structure: Composed of phosphate, deoxyribose sugar, and a nitrogenous base.
  • Nitrogenous Bases: Adenine (A), Thymine (T), Guanine (G), Cytosine (C).
  • DNA Ladder Model Components:
    • Backbone: Alternating phosphate and deoxyribose sugar.
    • Rungs: Nitrogenous bases.
  • Strand Orientation: Antiparallel.
  • Complementary Base-Pair Rule: Adenine (A) pairs with Thymine (T), Guanine (G) pairs with Cytosine (C).
  • Hydrogen Bonds:
    • A-T: 22 hydrogen bonds.
    • G-C: 33 hydrogen bonds.
  • Overall Shape: Double helix (twisted ladder).