Practice question

Ideal electrophoresis of a pure sample yields single sharp band at expected position. Appearance of multiple bands indicates heterogeneity within sample. Contaminating nucleic acids or proteins co-migrate at distinct positions, while isoforms differing in size, splicing variants, post-translational modifications, or conformational states also produce additional bands. Primer dimers or partial degradation generate secondary bands. High voltage, poor staining, or low sample volume affect band intensity and sharpness but typically do not create discrete extra bands. Thus multiple bands suggest contamination, isoforms, or degradation products requiring further purification analysis.