The ethidium bromide solution we will use in class is 10 mg/ml. We have added 4 µl to 100 ml of agarose gel mix. a) How many µg of EtBr did we add to each gel? 10mg/ml Times 1000= 10000microg/1000microliter 4 microliters added 40000/1000= 40 micrograms b) What is the final concentration of EtBr in the gel? c) How much EtBr solution at 1 mg/ml would be used to give 0.05 µg/ml EtBr final concentration? (Hint: determine dilution factor first) d) How many molecules of EtBr are in your gels? (EtBr formula weight 394.3.)