Question

Which of the following components bind to the solid column made of silica, under high salt concentration?

(a) Proteins

(b) Polysaccharides

(c) Both proteins and polysaccharides

(d) Plasmid DNA

I got this question at a job interview.

The doubt is from Purification of Plasmid DNA topic in section Basics of Genetic Engineering of Genetic Engineering

Answer 1

Correct choice is (d) Plasmid DNA

The best I can explain: Plasmid DNA binds to a solid support which is made of silica and under high salt concentrations. A high salt concentration doesn’t allow less polar molecules to bind such as polysaccharides and proteins. The binded DNA molecule is further eluted by using a low salt concentration.