Biochem 25: DNA Metabolism

Organisation alone is not enough. Information must be preserved through time, duplication, and stress. In this episode, Medlock Holmes examines DNA metabolism — the set of processes that ensure the genome is faithfully copied, vigilantly repaired, and resilient in the face of constant threat.DNA is not a static record. It is actively replicated, continuously monitored, and repeatedly repaired. Errors arise not from negligence, but from inevitability: thermal motion, chemical instability, radiation, and replication itself all conspire against fidelity. DNA metabolism exists because perfection cannot be assumed.Drawing on the mechanistic clarity of Lehninger Principles of Biochemistry and the clinically grounded treatment of replication and repair in Harper’s Illustrated Biochemistry, this episode explores DNA polymerases, proofreading, mismatch repair, excision repair, and double-strand break responses. We see how redundancy and surveillance are built into the system — not as luxury, but as necessity.Medlock learns that stability is an active achievement. When DNA metabolism fails, the consequences are cumulative: mutations accumulate, cells malfunction, and malignancy becomes possible. Cancer, ageing, and inherited disease all leave their fingerprints here.This episode reveals the genome not as fragile glass, but as a structure constantly under repair — strong precisely because it expects damage.Key Topics Explored* DNA replication and polymerase fidelity* Proofreading and error correction* Base excision and nucleotide excision repair* Mismatch repair and replication errors* Double-strand break repair mechanisms* Clinical relevance: cancer predisposition and genomic instability This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit drmanaankarray.substack.com/subscribe