Practice question

Magnetic bead purification uses paramagnetic particles coated with silica or carboxyl groups that reversibly bind nucleic acids. Under high salt and chaotropic conditions, DNA adsorbs to bead surface via electrostatic and hydrophobic interactions. An external magnetic field immobilizes beads, allowing washing to remove proteins, salts, and contaminants. Elution in low salt buffer releases pure DNA. This method avoids centrifugation and toxic organics, is automatable, and yields high purity. It differs from column chromatography, CTAB extraction, and isopropanol precipitation which do not use magnetic particles for solid-phase capture.