All of these are for objectives 3 and 4 at the analysis/application level 1. 10
ID: 133637 • Letter: A
Question
All of these are for objectives 3 and 4 at the analysis/application level 1. 10 bacteria were inoculated into 5ml rich media. Their doubling time is 30 minutes. They grew for 10 hours. What is the final cell density (cells/mL)? 2. How many bacteria are present after 51 hours if a culture is inoculated with 1 bacterium, with a generation time of 50 minutes? 3. How many initial cells are used to inoculate a culture that has 81,920 bacteria present after 20 hours of growth, with a doubling time of S hours? 4. If in 8 hours an exponentially growing cell population increases from 5 x 10f cells/ml to 5 x 102 celts/mt, what is number of generations that has occurred, growth rate and generation time for this organismiExplanation / Answer
1. Initial cell density (N0)= 102
Doubling time (td) = 30 minutes
Growth time (t) = 10 hours = 600 minutes
Number of generations (n) = t / td = 600 / 30 = 20
e0.301n = (Nt/N0)
=> e6.02 = Nt / 102
=> Nt = e6.02 * 102
=> Nt = 1.05*106 * 102
=> Nt = 1.05*108
Cell density = Nt / Volume = 1.05*108 / 5 = 2.1*107 cells/ ml
Cell density = 2.1*107 cells/ ml
2. Initial cell density (N0)= 1
Doubling time (td) = 50 minutes
Growth time (t) = 51 hours = 3060 minutes
Number of generations (n) = t / td = 3060 / 50 = 61.2
e0.301n = (Nt/N0)
=> e18.4212 = Nt / 1
=> Nt = e18.4212
=> Nt = 2.6*1018
Final count of bacteria = 2.6*1018 cells
3. Final cell density (Nt)= 81920
Doubling time (td) = 5 hours
Growth time (t) = 20 hours
Number of generations (n) = t / td = 20 / 5 = 4
e0.301n = (Nt/N0)
=> e1.204 = 81920 / N0
=> N0 = 81920 / e1.204
=> N0 = 81920 / 15.99 = 5123
Initial count of bacteria = 5123 cells
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