In: Biology
1. Given the vol of TE in which we re-suspended your DNA and the vol of DNA sample you digested for the gel, how many more digests could you run with the DNA you isolated? Please show your calculations with explanations.
2. We measured the concentration of your DNA spectrophotometrically, given the vol of the TE in which we re-suspended the DNA, and the concentration of you DNA in ng/ul, calculate the total amount of DNA you isolated in ug. Please show your calculations with explanations.
ng/ul | A260 | A280 | 260/280 | 260/230 | digest ul | DNA vol |
1283.55 | 25.671 | 17.022 | 1.51 | 0.57 | 1.5 | 100 ul |
From this table, I'm assuming the vol of DNA is 100 ul, the vol of TE is 1.5 ul, and the concentration of DNA in ng/ul is 1283.55. So I think I have all of the information needed, I just have no idea how to assemble it.
First I will take the second question that how much amount of DNA you have isolated.
Here the concentration of DNA is 1283.55 ng/ul and volume of TE is 1.5 ul
Here total amount of DNA that you have isolated is 1283.55 ng/ul * 1.5= 1925.325 ng
1925.325 ng/1000= 1.925325 ug (Total amount of DNA in ug)
Now come to first question, it is not define that how much ng or ug DNA you need for the digestion.
Generally in digestion you can take 50ng is considered that can easily visible on the gel. Lesser concentration can also visible on gel but 20ng reactions will dilute and will not good result.
I think in the last table where 100ul volume is given if take 1 ug of DNA is taken for digestion than only one reaction can be performed.
If take 1925.325 ng DNA and reaction is 100 ng than
1925.325/100= 19.253= 19 reactions can be performed.
One more thing that I would like to mention that measuring A280 = 17 is not considered for good because it show lot of standard deviation. Measurement A280 show minimum standard deviation between 0.1-1 absorbance. This gives you the correct measurement of DNA.