# Laboratory Calculations Problem Set #2

1. If 10x TBE contains 0.89 M Tris-borate, 0.89 M Boric acid, and 0.02 M EDTA, what is the Molar concentration of Tris-borate in 100 ml of 1x TBE?

2. How many ml of 0.5 M EDTA are required to make 100 ml of a 0.1 M EDTA solution?

3. If a solution of DNA is 3 mg/ml, 0.5 mg of DNA would be contained in how many ml?

4. If you have a 5x stock solution, how much of this stock would be needed to make 100 ml of a 1x solution? 10 ml of a 1x solution? 33 ml of a 1x solution?

5. How many grams of agarose are needed to make 100 ml of a 2% agarose solution?

6. How many ml of the detergent Nonidet P-40 would be used to make 43 ml of a 7% detergent solution?

7. An extraction buffer for DNA is stored as a 15x stock solution. How much of this stock solution would be required to make 7.5 ml of a 1x working solution? a 0.5x solution?

8. Given the following stock solutions: 1 M Tris, 0.5 M EDTA, 4 M NaCl, do the calculations necessary to make 1 L of a solution containing 100 mM Tris, 100 mM EDTA, 250 mM NaCl.

9. How many ml of a 1 x 10 cells/ml suspension should be used to plate out 500 cells/plate? 100cells/plate?

10. The following stock solutions are available to make a protein extraction buffer: 100% Nonidet P-40, 1 M Tris-Cl, and 0.5 M EDTA. What quantity of the original stocks will be needed to make 250 ml of buffer with the following final concentrations: 0.5% Nonidet, 150 mM Tris-Cl, and 10 mM EDTA?