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#DNA staining

2 public questions tagged with this topic.

Mutation and Mutagenesis

Ethidium bromide is a

Ethidium bromide is cationic phenanthridine dye with flat polycyclic ring system ideally dimensioned to intercalate between nitrogenous bases, binding with high affinity and enhancing fluorescence twentyfold enabling visualization of DNA under UV. Intercalation lengthens and rigidifies duplex, inhibits topoisomerases, and promotes polymerase slippage leading principally to frameshift events rather than point substitutions. Due to potent mutagenic and potential carcinogenic activity, laboratory handling requires protective measures and decontamination with activated charcoal or hypophosphorous

Ref: Lodish et al., Molecular Cell Biology, 9th ed., Chapter 9: Ethidium Bromide as Intercalating Agent

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Electrophoresis

Which stain allows DNA visualization under UV light?

DNA visualization requires a fluorophore excitable by UV transillumination. Ethidium bromide intercalates between base pairs and shows strong fluorescence enhancement upon binding, emitting orange light under UV. This allows detection of nanogram quantities of DNA within gel bands. Bromophenol blue and methyl blue are tracking dyes visible in white light, not fluorescent. Crystal violet stains proteins or bacterial cell walls and does not intercalate DNA. Therefore, ethidium bromide remains the prototypical UV-activated DNA stain, though safer alternatives like SYBR Green are now favored.

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.

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