Originally Posted by Hope2Pass
A flask is inoculated to a density of 3x10^3 cells/ml. What will be the density of cells in the culture after 50 minutes if the generation time is 20 mins and the lag time is 10 mins ?
You need to know the LESD process in this.
Log / Lag........... 10 minutes
Stationary.......... 10 min?
Decline / Death....10 min?
Only time they are dividing is in the exponential phase, after which there is no increase in numbers.
and the bacteria has 40 minutes to grow: 50 minutes - lag time (10 minutes) = 40 minutes
With the generation time of 20 minutes and 40 minutes to grow, you will have 2 generations.
You need to know this equation:
b = B x 2^n (This equation is an expression of growth by binary fission)
b = number of bacteria at the end of the time interval
B = number of bacteria at the beginning of a time interval
n = number of generations (number of times the cell population doubles during the time interval) in this case it is 2.
b = 3x10^3 cell /ml x 2^ n
In this case n = 2 because there are 2 generations during the 40 minutes
b = 3x10^3 cell /ml x 2^ 2
b = 3x10^3 cell /ml x 4
b = 12 x 10^3 cel/ml