Bacteria mean generation time

The second complication is that, whereas in animal tissues cellular proliferation is slow compared to the synthetis of soluble proteins, and, therefore, the synthetic of new ribosomes is n igible during an experiment lasting a few minutes, this is not so in bacteria where the mean generation time is very short. For E. ccli, for example, it is 50 min, and since in this time the ribosome content will double along with that of soluble protein, we see that in 2 min (which is the shortest time usually employed) 4 % of the ribosomal protein would be synthesized from labeled precursors—an amount which would completely obliterate the 0.1 % of transient precursor protein iidiich mi t be expected to be associated with the ribosomes. 

Application of the above equation will show that one bacterium will reproduce to 4.7(10 ) bacteria in one day assuming a generation time of 20 minutes. Using the dimension of a bacterium of 2 pm diameter by 12 /tm length, the volume of one bacterium is equal to 3.77(10 cubic meter. Thus, assuming that the density of the bacteria is the same as that of water, one bacterial cell will reproduce to (1000)(3.77) (10 )(5)(10 ) = 188,500,000 kg in 24 hours This mass is, of course, impossible to be obtained from one bacterinm in a day. What this means, though, is, that in a real-world situation, the bacterinm does not divide unrestricted, but is influenced by other environmental factors such as crowding and exhaustion of the food supply. 

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