Biological samples are first lysed and homogenized in the presence of a highly denaturing guanidine-thiocyanate–containing buffer, which immediately inactivates RNases to ensure intact RNA. Ethanol is added to provide appropriate binding conditions, and mixture is then applied to the spin-column, genomic DNA and total RNA bind to the same membrane. Finally, contaminants are efficiently washed away separately. High-quality gDNA and total RNA are then eluted in 30–100 μl water.