Question

1. If you want to design an experiment to measure the fluorescence emission of ethidium bromide, what would you choose as your excitation wavelength? What would you choose as your emission wavelength?

10 mer and EtBr 900.00 800.00 Trial 1 DNA+EtBr X Trial 2 DNA+EtBr+Drug 1 Intensity 700.00 600.00 500.00+ 400.00+ 300.00 200.00+ 100.00 A Trial 3 DNA+EtBr+Drug 2 Trial 4 DNA+EtBr+Drug 3 0.00 0.00 0.40 0.20 Ratio of [EtBry[DNA]bp

2. Which trial has the highest concentration of ethidium bromide incorporated into DNA? Which has the lowest? Explain using the concept of fluorescence quenching.

3. Which drug occupies the most sites on DNA? Which drug occupies the least? Explain using the concept of fluorescence quenching.

4. The ethidium bromide-DNA binding and the drug-DNA binding are both equilibrium reactions. Which drug has the highest K (equilibrium constant) for its binding to DNA?

Answer 1

1) ethidium bromide absorbs UV light at 300nm and 360nm, and emission at 590nm.detection limit of DNA is 0.5 to 5.0ng/band.

2)trial1 has the highest concentration of EtBr incorporated into DNA because it is capable of forming Vander wall interaction with base pair and trail 4 has minimum concentration of EtBr incorporated into DNA