Calculateur d'Activité (Becquerel)
Calculez l'activité radioactive en becquerels.
Doubling Time (td)
8.00 hours
Doubling Time (td) vs Time Elapsed (t)
Formule
## Cell Doubling Time During exponential growth, cells divide at a constant rate. The doubling time is the time required for the population to double. ### Formulas **Growth rate: k = ln(Nt/N0) / t** **Doubling time: td = ln(2) / k** **Generations: n = ln(Nt/N0) / ln(2)** These formulas assume exponential (log-phase) growth without nutrient limitation or inhibition.
Exemple Résolu
A culture grows from 100,000 to 800,000 cells in 24 hours.
- 01k = ln(800000/100000) / 24 = ln(8) / 24 = 2.079 / 24 = 0.0866 h⁻¹
- 02td = ln(2) / 0.0866 = 0.693 / 0.0866 = 8.00 hours
- 03Generations = ln(8) / ln(2) = 3.00 doublings
Questions Fréquentes
What are typical doubling times?
E. coli: 20-30 min. Yeast: 90-120 min. Mammalian cell lines: 18-30 hours. Primary human cells: 24-72 hours. Cancer cells vary widely: 12 hours to several days.
How do I ensure I am measuring exponential growth?
Cells must be in log phase (not lag or stationary phase). Take multiple time points and verify that ln(N) vs time is linear. Seeding density should be high enough to skip lag but low enough to avoid early confluence.
What about using OD instead of cell counts?
For bacterial cultures, OD600 is proportional to cell density in the linear range (OD 0.1-0.6). Above this, the relationship becomes nonlinear and samples should be diluted before reading.
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