You left to get lunch, and your lab partner\'s task was to quanitfy the DNA you

Question

You left to get lunch, and your lab partner's task was to quanitfy the DNA you previously isolated using nanodrop. However, the only thing you find on your bench upon your return is a note which reads the following: A260 = 0.074; A260/A280 = 1.81.

Since you are performing time-sensitive experiment that requires a starting amount of 1ug/ul of DNA and your partner left for the day, you must quickly determine the DNA concentration.

a) Discuss two strategies your patner and you applied during DNA extraction that makes you confident in 1.81 reading (convince us that your DNA is "clean")

b) Do you have enough pure DNA to proceed?

c) You notice that the struggling neighbor's DNA yield is 1.2 ug/ul, and her A260 = 0.045 and A280 = 0.03. You inquire, and she happily exlciams that the yield is sufficient to continue. Your advice to her is?

Explanation / Answer

DNA concentration = OD260 * 50 ng/ul * dilution

= 0.074 * 50 * 1 = 3.7 ng/ul.

1) during isolation procedure we added RNAse to remove RNA contamination and Proteinase to remove Protein contamination. so we are confident about the purity of the DNA.

2) we do not have enough amount of DNA. but if the nano derop reading of the DNA is 1000 times diluted sample than we have enough concentration to proceed further.

3) the ratio of A260/A280 = 0.045/0.03 = 1.5 which indicate that the preparation is contaminated with protein. our advice will be

a) prepare new DNA.

2) add proteinase to remove protein contamination.

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