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Molecular Basis of Inheritance - Coggle Diagram
Molecular Basis of Inheritance
DNA as Genetic Material
Transforming Principle
Griffith (1928): smooth vs rough strains
Avery, McCarty & MacLeod: DNA identified as the factor
Bacteriophage Evidence
Hershey & Chase (T2 phage)
Chargaff’s Rules
Base composition varies by species
A = T, G = C
Double‑Helix Model
Franklin’s X‑ray diffraction
Watson & Crick: antiparallel strands
DNA Replication
Semiconservative mechanism (Meselson & Stahl)
Initiation
Origins, replication bubbles, forks
Helicase, SSBPs, Topoisomerase
Elongation
Leading strand: continuous 5′->3′
Lagging strand: Okazaki fragments
Primase lays RNA primers
DNA ligase joins fragments
Proofreading & Repair
DNA polymerase proofreading
Mismatch‑repair enzymes
Nucleotide‑excision repair
Telomere Maintenance
Telomere shortening each cycle
Telomerase extends germ‑cell telomeres
Chromosome Structure & Packaging
Prokaryotic nucleoid supercoiling
Eukaryotic chromatin
Nucleosome “beads‑on‑a‑string”
30 nm fiber -> looped domains -> metaphase chromosome
Euchromatin (loose) vs heterochromatin (dense)
Histone‑tail modifications regulate expression
Evolutionary & Functional Significance
High‑fidelity replication preserves lineage
Mutations supply genetic variation
Chromatin dynamics influence gene accessibility