Intercalation of Base Analogs

    Acridine dyes are histological stains with planar three-ring structures that resemble purine + pyrimidine base pairs. If these base analogs intercalate ("slip") into the DNA molecule between two adjacent base pairs, the intercalated molecule may cause DNAPol to "stutter" and copy the molecule as an extra base pair. This introduces a frameshift mutation.

    Ethidium bromide (EtBr ) is widely used in molecular biology as a specific dye for staining DNA: the intercalated molecule fluoresces on exposure to ultraviolet light. EtBr may be incorporated into electrophoretic gels, or the gel may be stained after running. In Biol2250 labs, care should always be taken to avoid direct exposure either to gels or buffer that contains EtBr.

Figure ©2012 TA Brown, Introduction to Genetics (1st ed.); additional text ©2014 by Steven M. Carr