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Natural Science Forum / Biology / Microbiology / October 2006A question about replication of E.coli chromosome
Hi everyone. I got a question about the replication cycle of E.coli chromosome. Say, the growth condition is sufficient, then what determine the time of the cycle of replication ? And I want to know how the rate of synthesization of protein affect the time. Thanks in advance. This question is kind of vague. Anyway, the quickest E. coli can replicate is around 20 minutes. It's limited to this, really, due to its inability to grow any faster. Before a bacterium divides, it needs to replicate its chromosome (actually, it can replicate the chromosome quicker than it takes to divide the cell.....and most of the time, you can have 2, 4, 8....etc. numbers of chromosomes in the same cell). It also needs to expand its cell wall and double the number of ribosomes. This takes time.....about 20 minutes for E. coli under the best conditions. Any bacterial physiologists out there with more insight? --Alex ******************* Alex B. Berezow, Grad Student Dept. of Microbiology University of Washington School of Medicine Seattle, WA 98195 > Hi everyone. I got a question about the replication cycle of E.coli > chromosome. Say, the growth condition is sufficient, then what > determine the time of the cycle of replication ? And I want to know > how the rate of synthesization of protein affect the time. Thanks in > advance. I'm sorry for the "kind of vague". :-) What I really want to know is why some bacteria are different much clearly from each other on the replication time when they are all under the best conditions.Take E.coli and Mycobacterium tuberculosis for example. The other question is how the temperature affects the rate of the replication? Is it adjusted by the activities of the enzymes? HuskyPhD 写道： > This question is kind of vague. Anyway, the quickest E. coli can > replicate is around 20 minutes. It's limited to this, really, due to [quoted text clipped - 21 lines] > > how the rate of synthesization of protein affect the time. Thanks in > > advance. It takes E. coli 40 minutes to replicate its chromosome, no matter what the conditions. It takes another 20 minutes to complete necessary cellular process for division. The only reason that E. coli can have generation times of less than 60 minutes is that a given round of chromosomal replication does not have to be completed before the next round is initiated > This question is kind of vague. Anyway, the quickest E. coli can > replicate is around 20 minutes. It's limited to this, really, due to [quoted text clipped - 21 lines] >>how the rate of synthesization of protein affect the time. Thanks in >>advance.  SignatureLarry D. Farrell, Ph.D. Professor of Microbiology Idaho State University -- Posted via a free Usenet account from http://www.teranews.com Whoops, my bad. It's been a while since I studied this stuff. Yeah, Larry is right.....the chromosome takes longer to replicate than the cell takes to divide. I think Yang's question though, is "Why 20 minutes? Why not 5 minutes? And why are other bacteria slower?" To these questions, I don't really know. I suppose that it takes a certain amount of time to double the number of ribosomes, expand the cell wall, etc., and that E. coli simply can't go faster than 20 minutes. Other bacteria are just slower than E. coli. Keep in mind E. coli is pretty unusual.....MOST bacteria don't double in 20 minutes. That's why microbiologists and molecular biologists use E. coli....it's unusually fast. --Alex ******************* Alex B. Berezow, Grad Student Dept. of Microbiology University of Washington School of Medicine Seattle, WA 98195 > It takes E. coli 40 minutes to replicate its > chromosome, no matter what the conditions. It [quoted text clipped - 4 lines] > chromosomal replication does not have to be > completed before the next round is initiated Thanks a lot! I suppose that the time for the replication of chromosome may not differ as much as the generation time between E.coli and M.tuberculosis. Am I right? HuskyPhD 写道： > Whoops, my bad. It's been a while since I studied this stuff. Yeah, > Larry is right.....the chromosome takes longer to replicate than the [quoted text clipped - 28 lines] > > chromosomal replication does not have to be > > completed before the next round is initiated Thanks a lot! I suppose that the time for the replication of chromosome may not differ as much as the generation time between E.coli and M.tuberculosis. Am I right? HuskyPhD 写道： > Whoops, my bad. It's been a while since I studied this stuff. Yeah, > Larry is right.....the chromosome takes longer to replicate than the [quoted text clipped - 28 lines] > > chromosomal replication does not have to be > > completed before the next round is initiated > Thanks a lot! > I suppose that the time for the replication of chromosome may not > differ as much as the generation time between E.coli and > M.tuberculosis. > Am I right? Basically. When genome replication occurs, it runs at a specific rate as defined by the enzymes involved, which don't vary that much between different types of bacteria. The only thing that really relates to the length of time required for chromosomal replication, then, is the size of the chromosome. Initiation of chromosomal replication is linked to other functions in the cell that relate to cell division, so the cell doesn't just randomly make chromosomal copies that hang around in the cell. If it takes the cell a long time to get ready to divide, initiation of chromosomal replication will be delayed a long time. Therefore, generation times will vary tremendously but the time required to copy the genome will vary only to the extent that genome sizes vary between different types of bacteria. SignatureLarry D. Farrell, Ph.D. Professor of Microbiology Idaho State University -- Posted via a free Usenet account from http://www.teranews.com THANKS A LOT! ^_^ Larry Farrell 写道： > > Thanks a lot! > > I suppose that the time for the replication of chromosome may not [quoted text clipped - 24 lines] > Professor of Microbiology > Idaho State University |
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