Question

A culture with approximately 2x103 cells/mL were incubated. After 3 hours, the number of cells had increased to 3x105. a) How long was the generation time in minutes? b) How many generations have occurred?

Answer 1

Nt=N02^t

t= number of generations

N0= number of cells present initially

Nt= number of cells after t generations

Nt=3x10^5

N0=2x10^3

3x10^5=2x10^32^t

2^t=3x10^5/2x10^3

=150

2^t=150

taking log on both sides

tlog2=log150

t=log150/log2

=7.23

growth time=3 hours

1 hour= 60 minutes

so 3 hours= 360=180 minutes

so generation time= time of growth/number of generations

=180/7.23

=24.9 minutes

a) 24.9 minutes

b) number of generations=7.23