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Old 03-23-2011
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Bacteria Microbial replication question from Kaplan

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 ?
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Old 03-23-2011
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Quote:
Originally Posted by Hope2Pass View Post
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
Exponential..........20 min
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.

Quote:
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
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