Spanda
AliveFed · 0 events · t = 0.0 s

Full medium gradient. The cell should grow its own machinery and hold a positive energy charge.

Live trajectories
energy chargetransporterenzymeinternal waste
Cumulative entropy production0 kJ·mol⁻¹·K⁻¹ · strictly > 0

The second law, enforced per event: every reaction dissipates free energy to the bath. The curve only ever rises — there is no internal free-energy creation to draw on.

Energy charge
50%
ATP / (ATP + ADP) · 500 ATP
Cell inventory
Transporter (T)10
Enzyme (E)10
Building blocks120
Internal nutrient60
Internal waste8

When fed, the cell builds its own machinery (T, E climb from 10). Pull the gradient, cut the gene, or block export and watch it run down.

The 13-reaction model
ReactionΔG° (kJ/mol)Catalyst
Nutrient import-4T
Catabolism → ATP-36E
Waste export-3
Transcribe · T-11DT
Transcribe · E-11DE
Translate · T-22mT
Translate · E-22mE
Degrade · T-50
Degrade · E-50
Degrade · mRNA-T-50
Degrade · mRNA-E-50
Maintenance (ATP→ADP)-30
Why this is real, not a cartoon
  • Every rate pair obeys k_f/k_r = e^(−ΔG°/RT) exactly — the detailed-balance residual above is machine-zero.
  • Dynamics are a direct-method Gillespie SSA: discrete molecules, stochastic events, real waiting times.
  • Growth and all three death modes emerge — no event is scheduled, no death is coded.
  • The same engine, scaled to 2,069 reactions, is the syn3A model in the papers.

Faithful in-browser port of the program's digital_cell_toy engine. Representative ΔG° values for legibility; the published model uses full eQuilibrator data.