This chapter delves into the chemical and structural basis of genes, starting
with early investigations that linked genes to enzyme activity. It highlights significant
milestones, such as Beadle and Tatum's one-gene-one-enzyme hypothesis and Linus
Pauling's refinement to one-gene-one-polypeptide. The chapter also explores the
discovery of DNA's chemical composition, emphasizing contributions from scientists
like Miescher, Avery, and Levene. Chargaff's rules and the race to unveil DNA's doublehelix structure by Watson and Crick are discussed. Finally, it explains the mechanisms
of DNA replication, emphasizing the semiconservative model and the roles of leading
and lagging strands.
Keywords: Base pairing, DNA replication, DNA structure, Gene expression, Nucleic acids.
