The kit can be used with cultured cells and animal tissues. The purified genomic DNA is suitable for genotyping and other DNA analyses using PCR or DNA sequencing. And the purified total RNA is suitable for use in a variety of downstream applications, including: RT-PCR, RT-qPCR, Northern blotting, nuclease protection assays, cDNA library preparation after poly (A)+ selection, RNA sequencing and so on. Biological samples are first lysed and homogenized in a strong denaturant containing buffer, which immediately inactivates RNases to ensure isolation of intact RNA. After homogenization, the lysate is passed through a DNA binding column which traps the DNA on the column, while RNA can pass through the column with the flow-through (FT1). The DNA binding column is washed and then the genomic DNA is eluted by the Elution Buffer. On the other hand, ethanol is added to the RNA containing flow-through (FT1) from the first column. The mixture is then passed through an RNA binding Spin Column to which the RNA binds. Impurities are effectively removed by subsequent washing. The purified total RNA is then eluted by Elution Buffer and may be used in a variety of downstream applications.