Practice question

DNA microarray performance depends on Watson-Crick base pairing between immobilized probes and fluorescently labeled target nucleic acids. Under controlled temperature and salt concentration, complementary sequences form stable duplexes, while mismatched sequences are removed during stringent washes. The resulting hybridization signal strength reflects thermodynamic stability and target concentration, permitting quantitative comparison across samples. PCR amplification, competitive binding unrelated to nucleic acid complementarity, and northern transfer principles describe separate techniques. Specificity of hybridization ensures that even single-base mismatches reduce signal, enabling expression and genotyping applications.