Practice question

Southern blotting developed by E. M. Southern transfers electrophoretically separated DNA fragments from agarose gel onto nitrocellulose or nylon membrane, preserving spatial arrangement of bands. Detection uses labeled single-stranded DNA or RNA probe that hybridizes to complementary sequences through Watson-Crick base pairing, specifically A-T and G-C hydrogen bonding under controlled stringency and salt concentration. Base pairing confers high specificity enabling identification of particular genes, RFLP alleles, and transgene integrations. Other principles like fluorescence may label probe, but underlying capture relies fundamentally on nucleic acid complementarity and hybridization kinetics.