You are working as an undergraduate researcher and asked to help a graduate stud

Question

You are working as an undergraduate researcher and asked to help a graduate student track the growth of a bacterial culture. He started the culture in the morning but will be out of the lab for the rest of the day. He asks you note when the culture concentration reaches 2.5 x 106 cells/ml. You measure the cell concentration at 11:00am and note a concentration of 1 x 104 cells/ml. The next time you measure the concentration at 1:30pm it has jumped to 1 x 107 cells/ml.  What should you tell the graduate student concerning the time that the concentration reached the concentration that he specified? (Assume for this question that both of your measurements occurred during the exponential phase.)

Using exponential growth equations N=N02n

g=t/n and n=3.3(logN-logNo)

Explanation / Answer

exponential growth equations N = N02n

g=t/n and n=2.3(logN-logNo)

t = time = 2.5 hrs

Where N0 = Initial concentration, N = aconcentration after t time.

By substitutng the given values in the above equations, we will get,

Growth rate = (7-4)* 2.303/ 2.5 ==> Growth rate = 2.76/ hr.

Generation time or doubling time = 0.693* growh rate = 0.693* 2.76 = 1.91 hrs.

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