Question

What is the principle behind CsCl density gradient centrifugation in the context of DNA separation?

Options

• CsCl chemically bonds to DNA and causes it to precipitate at specific temperatures

• CsCl neutralizes the electric charge on DNA, allowing gravitational separation

• CsCl denatures DNA strands, separating them based on molecular weight alone

• CsCl ions form a density gradient, and DNA molecules migrate to settle at levels matching their own buoyant density

Answer 1

In CsCl density gradient centrifugation, the caesium chloride ions form a density gradient within the centrifuge tube (lighter at the top, denser at the bottom) when spun at extremely high speeds in an ultracentrifuge. DNA molecules migrate and form bands at positions matching their own buoyant density, allowing separation of heavy, light, and hybrid DNA molecules.