Molecular Basis of Inheritance – Class 12 Biology Notes | CBSE NCERT Based
📚 Chapter: Molecular Basis of Inheritance – Detailed Notes --- 🔸 1. Introduction This chapter explains how genetic information is stored, replicated, and expressed in living organisms through DNA and RNA. --- 🔹 2. DNA – The Genetic Material Full form: Deoxyribonucleic Acid Found in nucleus (eukaryotes), cytoplasm (prokaryotes) Proved by: ✅ Griffith's Transformation Experiment ✅ Avery-MacLeod-McCarty experiment ✅ Hershey-Chase experiment (Bacteriophage with radioactive sulfur and phosphorus) --- 🔹 3. Structure of DNA Double helix model by Watson and Crick Each nucleotide = phosphate + deoxyribose sugar + nitrogenous base Nitrogenous bases: Purines: Adenine (A), Guanine (G) Pyrimidines: Cytosine (C), Thymine (T) Base pairing: A = T (2 H-bonds), G ≡ C (3 H-bonds) Antiparallel strands (5′ → 3′ and 3′ → 5′) --- 🔹 4. Packaging of DNA In prokaryotes: Looped and held by non-histone proteins In eukaryotes: Histone proteins form nucleosomes – "Beads on string" structure --- ...