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#1
05-29-2013
 USMLE Forums Addict Steps History: Not yet Posts: 125 Threads: 17 Thanked 66 Times in 38 Posts Reputation: 76
baqterial generation

a flask is inoculated to a density of 3x10*3cell/ml,what is the denisty of cells in culture after 50 min if generation time is 20 min and lag time is 10min?
A 6X10*3
B 4 X10*3
C 12X 10*3
D 8 X10*3
E 2X10*3

#2
05-29-2013
 USMLE Forums Newbie Steps History: Step 1 Only Posts: 7 Threads: 0 Thanked 3 Times in 3 Posts Reputation: 22

Assuming resources are infinite, I would think that the bacteria has 2 generations of replication

inoculate so starting density is 3x10^3

wait 10 minutes for lag time

Then there is exponential growth.

So every cell divides into two. 3x10^3 * 2 = 6x10^3

This took 20 minutes, 30 minutes have elapsed since start

Because there is another 20 minutes. the cells divide again

6x10^3 * 2 = 12 x 10^3

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