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Sos response E. coli

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Sos response E. coli

Postby CarolineHope » Wed Feb 09, 2011 12:01 am


Im not sure i fully understand the SOS response in E. coli. Id like to know a bit more about it and know if it is possible that it reduces the time length usually required for E. coli to replicate its dna. I know that it allows the replication of the damaged dna but introduces mutations in it.

I did an experiment where we irradiated sodium azide sensitive E. coli with UV rays and it took only 30 min of incubation time after the irradiation for the E coli to show sodium azide resistance. Id like to know how E coli was able to show this new resistance after only 30 min of incubation. I know the SOS response sytem is responsible for these mutations but i dont see how 30 min only was long enough for this new resistance to appear. Can anybody help me?

Thanks a lot :)
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Postby DRT23 » Sun Feb 27, 2011 1:34 pm

The normal generation time for E. coli is about 20-30 minutes and there are thousands of bacteria in the petri dish. UV causes random mutations in their DNAs and some of them become sodium azide resistant by chance. In the genome of this lucky bacteria, there is a mutation in the gene which is responsible for sodium azide resistance/sensitivity and no other lethal mutations in any other region of their genomes. And the colonies that you can see in the petri at the end of the experiment are formed by this luckly bacteria :)
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Postby JackBean » Wed Feb 01, 2012 1:09 pm

also, the SOS response introduces new mutations ;)

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