Generation Counter
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In somatic mamalian cells, the telomeres cannot be copied in their full length by the polymerases, because they copy in one direction and so they would need to start *after* the end to copy the ends. That is somewhat the worse explanation you will ever read about this phenomenon, so googling a bit about "telomere" and say, "aging", won't harm you at this point. | In somatic mamalian cells, the telomeres cannot be copied in their full length by the polymerases, because they copy in one direction and so they would need to start *after* the end to copy the ends. That is somewhat the worse explanation you will ever read about this phenomenon, so googling a bit about "telomere" and say, "aging", won't harm you at this point. | ||
Is there a way to use this trick in bacteria? The problem is far from trivial since | Is there a way to use this trick in bacteria? The problem is far from trivial since | ||
| - | # bacteria usually digest linear DNA | + | # bacteria usually digest linear DNA and so it won't last for long |
# it is difficult to insure that that DNA gets only replicated once per generation (as plasmid tend to have asynchronous replication cycles?!?) | # it is difficult to insure that that DNA gets only replicated once per generation (as plasmid tend to have asynchronous replication cycles?!?) | ||
| - | + | # the determination of the actual number of generations would probably be statistical rather than exact, by filtering "telomeres" of different lengths (since depending on replication and shortening the longer strands will still be present to some extent), e.g. by electrophoresis, and determining the "telomeres" with the shortest length. | |
| + | |||
=Discussion= | =Discussion= | ||
>> for comments, questions and temporary remarks go to the [[Talk:Generation_Counter]] | >> for comments, questions and temporary remarks go to the [[Talk:Generation_Counter]] | ||
Back to [[ETH Zurich]] main page. | Back to [[ETH Zurich]] main page. | ||
Revision as of 10:58, 4 August 2005
Back to ETH Zurich main page.
Contents |
Intro
Cell generation counter.
Principle
A counter somehow triggered by cell division that allows the experimentator to track the number of generations.
The telomere approach
In somatic mamalian cells, the telomeres cannot be copied in their full length by the polymerases, because they copy in one direction and so they would need to start *after* the end to copy the ends. That is somewhat the worse explanation you will ever read about this phenomenon, so googling a bit about "telomere" and say, "aging", won't harm you at this point. Is there a way to use this trick in bacteria? The problem is far from trivial since
- bacteria usually digest linear DNA and so it won't last for long
- it is difficult to insure that that DNA gets only replicated once per generation (as plasmid tend to have asynchronous replication cycles?!?)
- the determination of the actual number of generations would probably be statistical rather than exact, by filtering "telomeres" of different lengths (since depending on replication and shortening the longer strands will still be present to some extent), e.g. by electrophoresis, and determining the "telomeres" with the shortest length.
Discussion
>> for comments, questions and temporary remarks go to the Talk:Generation_Counter
Back to ETH Zurich main page.
