Question 2 In a bacterial culture in which all cells are unable to synthesize le
ID: 178243 • Letter: Q
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Question 2
In a bacterial culture in which all cells are unable to synthesize leucine ( leu ), a potent mutagen is added, and the cells are allowed to undergo one round of replication. At that point, samples are taken, a series of dilutions is made, and the cells are plated on either minimal medium or minimal medium containing leucine. The first culture condition (minimal medium) allows the growth of only leu+ cells, while the second culture condition (minimal medium with leucine added) allows growth of all cells. The results of the experiment are shown in the table above.
How many mutant cells are in the bacterial culture after one round of replication in the presence of mutagen?
3 x 107 cfu/ml
2.1 cfu/ml
21 x 101 cfu/ml
3 x 10-7 cfu/ml
3 x 101 cfu/ml
21 x 10-1 cfu/ml
Culture Condition Dilution Colonies Minimal medium 101 21 Minimal medium + leucine 107 3Explanation / Answer
To calculate the number of mutant cells in the culture, one must multiply the dilution factor to the number of cells.
Thus, the answer would be 21 x 101 cfu/ml (=c)
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