Which tracking dye is used in electrophoresis to monitor the progress of DNA migration?
Tracking dyes are anionic dyes co-migrating with nucleic acids to visually monitor electrophoretic progress without staining DNA. Xylene cyanol FF migrates at approximately 4 kb in 1 percent agarose, while bromophenol blue migrates near 300 bp, allowing estimation for different fragment ranges. Xylene cyanol is specifically preferred for larger fragments because its slower mobility prevents premature exit. Ethidium bromide is an intercalating stain, not a front marker. TEMED is a polymerization catalyst, and agarose is the support matrix. Hence xylene cyanol serves as a reliable migration indi
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.