Circadian Rhythm — Goodwin Oscillator

Negative feedback loop generates ~24-hour biological clock

Light input: 0.5

Repression (n): 10

Degradation (k): 0.5

mRNA prod (v): 1.0

Time: 0h | mRNA: – | Protein: –

Goodwin (1965) oscillator: mRNA (M) → Protein (P) → Repressor (R) → inhibits mRNA. Hill coefficient n controls nonlinearity needed for oscillations. mRNA=gold, Protein=cyan, Repressor=magenta.