DNA was proven to be the genetic material through Griffith's transformation experiment (1928), Avery's enzymatic identification (1944), and Hershey-Chase's radioactive phage experiment (1952).

Watson and Crick's double helix model (1953) described DNA as a right-handed antiparallel double helix, with A=T (2 H-bonds) and G≡C (3 H-bonds) satisfying Chargaff's base-pairing rules.

In eukaryotes, DNA is wound around histone octamers (2×H2A, H2B, H3, H4) to form nucleosomes, which compact further into chromosomes; H1 is the linker histone, not part of the octamer.

DNA replication is semiconservative (proven by Meselson and Stahl in 1958), producing two daughter molecules each with one parental and one new strand.

Helicase unwinds the helix; primase synthesizes RNA primers; DNA Pol III synthesizes new strands 5'→3'; DNA Pol I removes primers; ligase joins Okazaki fragments on the lagging strand.

The central dogma (DNA→RNA→Protein) is executed by RNA polymerase (transcription, no primer needed) and ribosomes (translation, at three sites: A, P, E).

Eukaryotic pre-mRNA undergoes 5' capping, 3' polyadenylation, and intron splicing before translation.

The genetic code has 64 codons: 61 sense codons for 20 amino acids, 3 stop codons (UAA, UAG, UGA), and the universal start codon AUG (methionine); the code is degenerate, non-ambiguous, non-overlapping, and universal.

The Lac operon exemplifies negative inducible regulation: allolactose (not lactose itself) inactivates the lacI-encoded repressor, releasing the operator and allowing transcription of lacZ, lacY, and lacA.

The Human Genome Project identified ~3.2 billion base pairs and ~20,000–25,000 genes in the human genome, and DNA fingerprinting uses VNTRs detected by Southern blotting for individual identification.