Question

Which of the following is correct with respect to caesium chloride centrifugation?

(a) Caesium is light in weight

(b) The dissolution of caesium and nucleic acids leads to the formation of gradients

(c) According to the amount of supercoiling and A+T content, the DNA settles

(d) Nicked DNA settles below than supercoiled DNA

I had been asked this question during an online interview.

I want to ask this question from Purification of Plasmid DNA topic in portion Basics of Genetic Engineering of Genetic Engineering

Answer 1

The correct choice is (b) The dissolution of caesium and nucleic acids leads to the formation of gradients

For explanation I would say: Caesium chloride is heavy and when the nucleic acid is dissolved with it, density gradients are formed. According to the extent of supercoiling and G+C content, settling of DNA takes place. The nicked DNA settles above than the nicked DNA.