For some DNAs it is possible to separate the two strands aft

For some DNAs it is possible to separate the two strands, after denaturation, in a CsCl gradient.

Part A

What property of any DNA determines where it will band in a CsCl gradient?

Part B

What kind of DNA might have two strands that differ sufficiently in this property that they could be separated after denaturation?

Solution

CsCl density gradient centrifugation is used to measure the density of the DNA. CsCl forms a density gradient during centrifugation with the most dense at the bottom.

A. DNA with different densities can be separated based on CsCl density gradient centrifugation. They are with different densities because of different A-T or G-C content. So density of DNA or AT or GC content determine the band in CsCl density gradient.

B. Adenine pairs with thymine with two bonds whereas guanine base pairs with cytosine with 3 base pairs. So GC pair needs more temperature to get denatured. So DNA with GC pairs might have two strands that differ sufficiently in this property that could be separated after denaturation.