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Syafiq94 Syafiq94
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11 years ago
how to prove that the experiment was semi conservative not dispersive??
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#1
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11 years ago
Wikipedia explains everything: http://en.wikipedia.org/wiki/Meselson%E2%80%93Stahl_experiment#Experimental_procedure_and_results

Specifically:
E. coli cells with only 15N in their DNA were transferred to a 14N medium and were allowed to divide;

After 2 divisions we measure the density of DNA molecules:
DNA from cells after two replications had been completed was found to consist of equal amounts of DNA with two different densities, one corresponding to the intermediate density of DNA of cells grown for only one division in 14N medium, the other corresponding to DNA from cells grown exclusively in 14N medium. This was inconsistent with dispersive replication, which would have resulted in a single density, lower than the intermediate density of the one-generation cells, but still higher than cells grown only in 14N DNA medium, as the original 15N DNA would have been split evenly among all DNA strands.
I think wikipedia explains your question very well. If you don't understand something, ask.
Syafiq94 Author
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#2
11 years ago
Quote from: Alexx (11 years ago)
Wikipedia explains everything: http://en.wikipedia.org/wiki/Meselson%E2%80%93Stahl_experiment#Experimental_procedure_and_results

Specifically:
E. coli cells with only 15N in their DNA were transferred to a 14N medium and were allowed to divide;

After 2 divisions we measure the density of DNA molecules:
DNA from cells after two replications had been completed was found to consist of equal amounts of DNA with two different densities, one corresponding to the intermediate density of DNA of cells grown for only one division in 14N medium, the other corresponding to DNA from cells grown exclusively in 14N medium. This was inconsistent with dispersive replication, which would have resulted in a single density, lower than the intermediate density of the one-generation cells, but still higher than cells grown only in 14N DNA medium, as the original 15N DNA would have been split evenly among all DNA strands.
I think wikipedia explains your question very well. If you don't understand something, ask.

ooo..so basically after the second generation only we cud conclude that it is a semi conservative?? cuz one generation alone is not valid to draw the conclusion??
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#3
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11 years ago
Exactly. With one division we can only exclude the conservative replication.
Syafiq94 Author
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#4
11 years ago
ooo.. i c
so lets say the dispersive replication occured, what are we expect to see in second generation?
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#5
Valued Member
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11 years ago
If we had dispersive replication, then the 15N would be randomly distributed after each DNA replication. This practically means that it would be almost impossible to have any pure DNA molecule (either 14N or 15N). The result would be that all DNA molecules would have density intermediate of the pure-14N and the pure-15N DNA molecules.
Syafiq94 Author
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#6
11 years ago
ooo...ok thx. got my doubt relieved
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