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Home Q & A Board Biology-Related Homework Help Cell Biology
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florapt93 florapt93
wrote...
11 years ago


You want to determine the concentration of plasmid DNA (i.e. it is double-stranded) in a stock tube. You dilute it by mixing 22 microlitres of your stock DNA with water to obtain a final volume of 1 mL. You obtain an absorbance reading at 260 nm of 0.15 using a standard 1-cm-wide cuvette. What is the concentration of DNA in your original stock tube?
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wrote...
#1
11 years ago
double-stranded DNA = 50 ug x OD260 x dilution factor

http://matcmadison.edu/biotech/resources/methods/labManual/unit_4/exercise_15.htm

good luck.
wrote...
#2
11 years ago
An OD260 of 1 is equivalent to 50 micrograms/ml.

Concentration of DNA was 0.15 X 50 micrograms/ml = 7.5 micrograms/ml.

You diluted 22 microlitres into 1000

Your initial concentration was (1000/22) X 7.5 micrograms/ml = 340.91 micrograms/ml.
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