This comprehensive course explores the intricate world of nucleic acid metabolism and genetic information flow. It begins with an in-depth study of purine and pyrimidine biosynthesis, including their regulatory mechanisms, and extends to the structure and properties of nucleosides and nucleotides. The biosynthesis of deoxyribonucleotides and thymidylate is covered, along with salvage pathways. The course then delves into DNA and chromosome structure, examining the evidence for DNA as the carrier of genetic information and exploring its primary, secondary (A, B, and Z forms), and tertiary structures. Students learn about the elucidation of DNA structure, including the Watson and Crick double helix model, and the structural differences between RNA and DNA. DNA sequencing methods and chromosomal organization, including nucleosome structure, are also addressed. The mechanism of DNA replication in both prokaryotes and eukaryotes is thoroughly explored, covering the evidence for semi-conservative replication, DNA replicating enzymes, and the directionality of replication. Finally, the course examines transcription mechanisms in prokaryotes and eukaryotes, the features of transcription units, characteristics of different RNA types, RNA modification and processing, and the phenomenon of reverse transcription. This comprehensive approach provides students with a solid foundation in molecular genetics and biochemistry.