Visualization of nucleic acids and proteins in electrophoresis gels

(a) The nucleic acids DNA and RNA are visualized using the compound ethidium bromide (EtBr) that binds to nucleic acid molecules and emits fluorescent light when excited by ultraviolet light. Molecular weight size markers in lanes 1 and 8 (bp = base pairs) aid in determining the size of molecules in the different bands in the experimental lanes 2 through 7.

(b) General protein stains bind to proteins in electrophoresis gels to reveal bands. Protein standards in lane 1 (kDa = kilodaltons) aid in determining the sizes of proteins in experimental lanes 2 through 4.