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Why is the DNA in eukaryotes an open ended string rather than a closed loop?
DNA in Eukaryotes: Open Ended Strings vs Closed Loops
- Thread starter arildno
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In summary, because linear DNA is easier to recombine and is more stable, it is better suited for sexual reproduction.
- #2
spuriousmonkey
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because it is too long to be in a loop?
- #3
Monique
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..something with D-branes.. I don't remember 
But seriously, it is a good question.. let's turn it around: why is the DNA in prokaryotes circular and when did the separation between circular and linear DNA start. I guess spuriousmonkey has a point.
But seriously, it is a good question.. let's turn it around: why is the DNA in prokaryotes circular and when did the separation between circular and linear DNA start. I guess spuriousmonkey has a point.
- #4
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This is how I think about it:
that by using an open ended string form, it is easier to build up
a more complex organism which might carve out new ecological niches for themselves.
But since this is wild, unsubstantiated speculation from my side, I wanted to hear an expert's view on the matter..
that by using an open ended string form, it is easier to build up
a more complex organism which might carve out new ecological niches for themselves.
But since this is wild, unsubstantiated speculation from my side, I wanted to hear an expert's view on the matter..
- #5
iansmith
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I don't think it is a question of length. Many bacteria have more than one chromosome and if you add all the genetic material (including plasmid) some bacteria have large genome. Linear chromsome tend to be unstable if some component are not present. Circular chromosome can be done artificially in yeast (http://www.nature.com/cgi-taf/DynaPage.taf?file=/ng/journal/v20/n2/abs/ng1098_203.html)
I think the difference between linear and circular is probably due to their distinct evolution and early in their evolution, eukaryotes acquire genes that stabilize the linear form. As far as complexity and exploting unique niche, bacteria are ahead of eukaryotes. Linear chromsome seems better suite for sexual reproduction. Recombination between two linear chromosome seem to be easier than circular DNA.
This is paper on the evolution of linear chromosome in bacteria.
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T2W-405SX5F-1&_user=458507&_handle=B-WA-A-A-BW-MsSAYZW-UUA-AUYZAZDVBE-AUYBDVYWBE-BEBWEBBUY-BW-U&_fmt=summary&_coverDate=05%2F05%2F2000&_rdoc=1&_orig=browse&_srch=%23toc%234929%232000%23998139997%23192052!&_cdi=4929&view=c&_acct=C000022002&_version=1&_urlVersion=0&_userid=458507&md5=66cbcaff630244073273ac3dca1eed2f
I think the difference between linear and circular is probably due to their distinct evolution and early in their evolution, eukaryotes acquire genes that stabilize the linear form. As far as complexity and exploting unique niche, bacteria are ahead of eukaryotes. Linear chromsome seems better suite for sexual reproduction. Recombination between two linear chromosome seem to be easier than circular DNA.
This is paper on the evolution of linear chromosome in bacteria.
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T2W-405SX5F-1&_user=458507&_handle=B-WA-A-A-BW-MsSAYZW-UUA-AUYZAZDVBE-AUYBDVYWBE-BEBWEBBUY-BW-U&_fmt=summary&_coverDate=05%2F05%2F2000&_rdoc=1&_orig=browse&_srch=%23toc%234929%232000%23998139997%23192052!&_cdi=4929&view=c&_acct=C000022002&_version=1&_urlVersion=0&_userid=458507&md5=66cbcaff630244073273ac3dca1eed2f
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- #6
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iansmith, great!
So, linear DNA is the best tool for gene-mixing when gene-mixing is to occur by means of sexual reproduction?
So, linear DNA is the best tool for gene-mixing when gene-mixing is to occur by means of sexual reproduction?
- #7
Monique
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I think he has a very good point too.. on average 40 cross-overs occur during meiosis, I don't see that happening with circular DNA.. :)
1. What is the difference between open ended strings and closed loops in DNA in eukaryotes?
Open ended strings refer to linear DNA molecules that have free ends, while closed loops refer to circular DNA molecules that have no free ends.
2. How do open ended strings and closed loops affect the structure of DNA in eukaryotes?
The presence of open ended strings and closed loops affects the overall compactness and stability of DNA in eukaryotes. Closed loops are more tightly packed and stable, while open ended strings are more susceptible to damage and can be more easily manipulated.
3. Are open ended strings or closed loops more common in eukaryotic DNA?
Closed loops are more common in eukaryotic DNA, as they are found in the mitochondria and chloroplasts of cells. However, open ended strings can also be present in certain regions of the genome.
4. What is the role of open ended strings and closed loops in DNA replication?
Closed loops play a crucial role in DNA replication, as they allow for the continuous replication of DNA without any interruptions. Open ended strings, on the other hand, require special enzymes to repair and reattach the free ends after replication.
5. Can open ended strings and closed loops coexist in the same eukaryotic cell?
Yes, open ended strings and closed loops can coexist in the same eukaryotic cell. As mentioned before, open ended strings can be found in certain regions of the genome, while closed loops are more common in specialized organelles such as mitochondria and chloroplasts.
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