A DNA plasmid has an A??? of 1.6 (1 cm path length) and is 3,000 bp in size. 1. What is the concentration of the plasmid DNA in ng/µl? A. 32 B. 64 C. 80 D. 100 E. 128 2. Prepare 50 µl of this plasmid DNA so that it has a final concentration of 30 ng/µl. To achieve this you pipette how many µl of the plasmid DNA? A. 15.0 B. 18.8 C. 23.4 D. 53.3 E. 133.3 3. What is the molarity of this 30 ng/µl plasmid solution (assume a base pair weighs 660 g/Mole)? A. 15 nM B. 30 nM C. 15 µM D. 30 µM E. 60 µM
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To calculate the concentration of the plasmid DNA in ng/ul, we need to use the formula: Concentration (ng/ul) = (Axco x dilution factor x 50 ng/ul) / DNA size (bp) where Axco is the absorbance at 260 nm and 1 cm path length, and the dilution factor is the factor Show more…
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From a small culture, you have purified the DNA of a recombinant plasmid. You add 275 μL of elution buffer to resuspend the DNA. You pipet 1 μL of the resuspended DNA with 229 μL of distilled water for a total of 230 μL. You measure the absorbance of the diluted sample at 260 nm and 280 nm in the spectrophotometer and obtain the following readings: A260 = 0.622; A280 = 0.086. 1. What is the DNA concentration of the 275 μL plasmid miniprep in micrograms per microliter? Answer to three decimal places: 2. How much total DNA in micrograms was purified by the plasmid prep procedure? Answer to one decimal place.
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From a small culture, you have purified the DNA of a recombinant plasmid. You add 275 mL of elution buffer to resuspend the DNA. You pipette 1 mL of the resuspended DNA with 229 mL of distilled water for a total of 230 mL. You measure the absorbance of the diluted sample at 260 nm and 280 nm in the spectrophotometer and obtain the following readings: A260= 0.622; A280= 0.086. 1. What is the DNA concentration of the 275 mL plasmid miniprep in micrograms per microliter? 2. How much total DNA in micrograms was purified by the plasmid prep procedure? 3. What is the A260/A280 ratio of the purified DNA? 4. A DNA solution has an A260 value of 0.749. Using Beer's Law, what is the DNA concentration in micrograms of DNA/mL? 5. A solution of DNA has an A260 of 0.208. What is its millimolar concentration?
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