In Meselson and Stahl\'s experiment, what was the purpose of centrifuging DNA in
ID: 170824 • Letter: I
Question
In Meselson and Stahl's experiment, what was the purpose of centrifuging DNA in a solution of cesium chloride.
Multiple Choice
The cesium chloride acted as a buffer to stabilize and protect extracted DNA.
The cesium chloride caused the DNA of early generations of bacterial cells to be heavier than the DNA of later generations of bacterial cells, thereby allowing Meselson and Stahl to determine that DNA replication is semiconservative.
The cesium chloride precipitated the DNA out of solution so that it could be isolated, purified, and characterized.
The cesium chloride broke the DNA at specific sequences, creating fragments of varying sizes.
The cesium chloride provided a medium of variable density, so that DNA of different density would aggregate in specific regions.
Explanation / Answer
In Meselson Stahl experiment they proved that the DNA replication process is semi conservative. they done this by density gradient centrifugation of DNA IN cscl. the purpose of centrifising DNA in Cscl was- to separate DNA based on density. DNA is mixed with cscl and centrifuged at 50,000 rpm. after centrifugation light DNA is found at the top and heavy in the bottom. as cscl gradient forms DNA comes to equilibrium in the gradient where its density is equal to surrounding cscl.
in the above question the correct statement are- it allow meselson and stahl to determine DNA replication is semi conservative.
after a sufficient time high speed centrifugation an equilibrium between sedimentation and diffusion is reached at which a linear gradient of increasing density exists from top to bottom of tube. DNA was labelled with N 15 HEAVY ISOTOPE.
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