Practice question

Ethidium bromide is a planar intercalating dye that inserts between stacked base pairs of double-stranded DNA regardless of topology, sequence, or labeling status. Upon UV illumination at 300 nm, intercalated dye fluoresces bright orange, revealing all DNA present in gel lane. It does not differentiate labeled versus unlabeled molecules, linear versus circular conformations, as intercalation depends only on double helix presence. Specialized methods like autoradiography detect only radioactive termini, while EtBr provides universal visualization of total DNA population for size estimation after restriction digestion and cloning verification.