Practice question

CTAB (cetyltrimethylammonium bromide) is a cationic detergent preferentially used for plant DNA extraction. Plant cells contain large amounts of polysaccharides, polyphenols, and secondary metabolites that co-precipitate with DNA and inhibit downstream PCR. CTAB forms insoluble complexes with nucleic acids at low salt, but at high salt concentrations above 0.7 M NaCl, it forms complexes with acidic polysaccharides and proteins while DNA remains soluble, allowing their removal. Subsequent dilution precipitates CTAB-DNA complex. It is less effective for animal tissues or RNA purification.