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A culture was inoculated with 20 bacteria and incubated for 6hours. The final number of bacteria in the culture was 7 x 10^6cells in the culture. What was the doubling time of this strain?(Make sure that you calculate the doubling time two ways: using theequation and by reasoning it out.) Double time ____________
To calculate the doubling time for a strain, we need to know the starting and ending number of cells in the culture, as well as the time that has elapsed. We also assume that every time a cell divides, it produces two daughter cells. For example, to go from 1 to 16 cells, we need four divisions (1→2→4→8→16). If these four divisions took 1 hour (6o minutes) to complete, then each division takes 15 minutes (doubling time = time elapsed/#of divisions). So the key is to find the number of divisions and divide the time the culture was growing by this number. We can calculate the number of divisions (n) from the following equation: Nf​=No​×2n . This equation tells us how the cell numbers present in a culture at the beginning (No​) and at the end (Nf​) are related to the number of cell divisions (n). If we solve for n,n=log(Nf​/No​)/log(2). Since doubling time (Td​)= elapsed time (t) / # of divisions ( n ), we get the final equation: Td​=txlog(Nf​/No​)log2​