Practice question

Southern blotting is classical technique established for specific DNA detection within heterogeneous genomic DNA population. Purified DNA is cut with restriction endonucleases, size-fractionated on agarose, denatured to single-stranded form, transferred to membrane via capillary action, and hybridized with labeled probe complementary to gene of interest. Visualization confirms presence, copy number, size, and rearrangement status of locus. Applications include mutation detection, RFLP mapping, and transgene integration analysis. In contrast, Northern blotting detects mRNA, Western detects proteins via antibodies, and lectin blotting detects carbohydrate moieties, demarcating Southern's DNA-specific role.