During Meselson and Stahl’s experiments, heavy DNA was distinguished from normal DNA by centrifugation in |
|||||||
a) |
CsOH gradient |
b) |
|
c) |
|
d) |
CsCl gradient |
During Meselson and Stahl’s experiments, heavy DNA was distinguished from normal DNA by centrifugation in |
|||||||
a) |
CsOH gradient |
b) |
|
c) |
|
d) |
CsCl gradient |
(d)
In Meselson and Stahl’s experiment, bacterial cells were grown for several generations in a medium containing a heavy isotope of nitrogen and then, were transferred to a new medium containing the normal lighter isotope
. At various times thereafter, samples of bacteria were collected and their DNA was dissolved in a solution of cesium chloride, which was spun rapidly in a centrifuge. Because the cesium ion is so massive, it tends to settle towards the bottom of the spinning tube, establishing a gradient of caesium density.