🧬 Biology Series · Exhibit 09

Blueprint of Life

The molecule that runs every living cell — explored in 3D. Then watch it choreograph its own duplication: mitosis builds an exact copy; meiosis shuffles the deck and deals four new hands.

3D DNA helix A-T · G-C base pairs Mitosis vs. meiosis Crossover / recombination 10.5 bp/turn · 3.4 Å rise
Section 1

3D DNA Double Helix

Watson & Crick's B-form helix: ~10.5 base pairs per turn, 3.4 Å rise per base pair, right-handed twist. Drag to rotate, scroll to zoom. Hover a base pair to see the pairing rule and hydrogen bond count. Toggle the major/minor groove overlay or adjust sequence length with the slider below.

Display options
Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)
Phosphate backbone
Major groove
Minor groove

Section 2

Mitosis vs. Meiosis Simulator

Two canvases. One story, two endings. Mitosis: one diploid parent splits into two identical diploid daughters — the body's workhorse. Meiosis: one diploid parent produces four haploid gametes, with crossover events that reshuffle maternal and paternal chromosomes before they separate. Play, pause, or step one phase at a time. Watch the coloured chromosome bars to see where recombination swaps segments.

Mitosis Diploid → 2 Diploid
Interphase
Meiosis Diploid → 4 Haploid
Interphase
Crossover in meiosis: During prophase I, homologous chromosomes pair up and exchange segments at points called chiasmata. Each coloured bar represents a chromosome — watch the maternal (solid) and paternal (striped) segments swap after crossing over. This is the same recombination process explored in Combinatorial Bloom.
2
Daughter cells from mitosis — genetically identical
4
Gametes from meiosis — each genetically unique
46
Human chromosomes in a diploid somatic cell
23
Chromosomes in a human gamete (haploid)
~2–3
Crossover events per human chromosome pair per meiosis
8m
Possible gamete combinations from independent assortment alone (m = chromosome pairs)

References

Scientific Foundation

Every structural and process detail in this exhibit is grounded in peer-reviewed molecular biology and cell biology literature.

Structure · 1953

Watson & Crick — "Molecular Structure of Nucleic Acids"

The original letter proposing the antiparallel double-helix model for DNA, with the iconic note that the specific base pairing immediately suggests a copying mechanism. Nature 171:737–738.

doi:10.1038/171737a0
X-ray Data · 1953

Franklin & Gosling — "Molecular Configuration in Sodium Thymonucleate"

Photo 51 and the precise X-ray diffraction measurements of B-form DNA — 3.4 Å rise per residue, 34 Å per turn — that underpinned Watson and Crick's model. Nature 171:740–741.

doi:10.1038/171740a0
Textbook · Current

Alberts et al. — Molecular Biology of the Cell (7th ed.)

The standard reference for DNA structure, base-pair geometry, replication machinery, and the molecular choreography of mitosis and meiosis. W.W. Norton / Garland Science, 2022.

Garland catalogue
Recombination · 2007

Baudat & de Massy — "Regulating Double-Stranded DNA Break Repair in Mammals"

Mechanistic review of meiotic recombination: how PRDM9 marks hotspots, how double-strand breaks are introduced by SPO11, and how crossover vs. non-crossover outcomes are regulated. Nature Reviews Genetics 8:517–529.

doi:10.1038/nrg2123
Cell cycle · 2004

Morgan, D.O. — The Cell Cycle: Principles of Control

Comprehensive treatment of cyclin–CDK regulation, checkpoint mechanisms, and the phase-by-phase choreography of mitosis and meiosis. New Science Press / Sinauer, 2007.

NCBI Bookshelf
Review · 2017

Zickler & Kleckner — "Meiotic Chromosomes: Integrating Structure and Function"

Authoritative review of synaptonemal complex formation, crossover designation, and the mechanical separation of homologs in meiosis I versus sister chromatids in meiosis II. Annual Review of Genetics 33:603–754.

doi:10.1146/annurev.genet.33.1.603