identify the four phases of the growth curve calculate generation time make use of the growth curve...
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•Identify the four phases of the growth curve
•Calculate generation time
•Make use of the growth curve
OBJECTIVES
Growth
• an orderly increase in cell numbercell division (细胞分裂)
• a developmental program superimposed upon this increasecell differentiation (细胞分化)
Binary Fission
20, 21, 22, 23, 24, 25, 26……
1, 2, 4, 8, 16, 32, 64……
Parent cell
Daughter cell
Daughter cell
Stationary phase – nutrients becoming limiting or waste products becoming toxic– secondary metabolism
– death rate = division rate
The generation time of a culture is defined as
A. the time it takes a cell to divide.
B. the time it takes the culture to begin growth.
C. the interval of time between the end of log phase to the stationary phase of growth.
D. the period of time it took for the organism to appear on earth.
E. how long the culture has been growing.
世代时间
Bacterium MediumGeneration Time
(minutes)
Escherichia coli Glucose-salts 17
Bacillus megaterium Sucrose-salts 25
Streptococcus lactis Milk 26
Streptococcus lactis Lactose broth 48
Staphylococcus aureus Heart infusion broth 27-30
Lactobacillus acidophilus Milk 66-87
Rhizobium japonicum Mannitol-salts-yeast extract 344-461
Mycobacterium tuberculosis Synthetic 792-932
Treponema pallidum Rabbit testes 1980
Calculation of Generation Time
G = t/n G ---generation time (time for the cells to divide) t---time (interval in hours or minutes) n---number of generations (number of times the cell population doubles during the time interval)
Solve for nlog N2 = log N1 + nlog2 n = log N2 - log N1 log2 n = log N2 - log N1 0.301 n = 3.3 log N2/ N1
N1 = number of bacteria at the beginning of a time interval N2 = number of bacteria at the end of the time interval
N2 = N1 × 2n (This equation is an expression of growth by binary fission)
Solve for G G = t/n G = t 3.3 log N2/ N1
A bacterium with a generation time of 0.5 hours will grow from a population of 103 to 109 cells, in about how many hours?
A. 25B. 3C. 40D. 20E. 10
Solve for G G = t / n G = t 3.3 log N2/ N1
•Bacteria from_______ phase can served as “seed” to another culture medium effectively, to decrease the lag phase
•Bacteria from_______ phase have the most typical morph -ological, biochemical and physiological features
•Bacteria from_______ phase can be used to screen medicine
Use of the
Growth curve
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