## Sample Calculations I

1) Make a 120 ml agarose gel of 0.7% (w/v) that is 0.5X TBE. The TBE (Tris, Borate, EDTA) stock is 5X and FW agarose is 210.

2) You have a 50X stock of buffer and you need 150 µl of 1X. How do you make this?

3) You have a DNA solution that is 125 µl; how much ethanol do you add if you add 2X the volume of ethanol?

4) Make 500 ml of a 10X TE stock (Tris, EDTA). 1X TE is 10mM Tris and 1mM EDTA. FW of Tris is 121.1 and EDTA is 187.

5) You want to digest 2 µg of DNA with BamH I; your DNA stock is 1.2 mg/ml. Use 1 µl of Bam and get your final volume to 30 µl. You need to have final concentrations of buffer and BSA (bovine serum albumin) to 1X but their stocks are 10X(buffer) and 100X(bovine serum albumin). Make that mixture.

6) Make 500ml the following stock solution: 0.6 M Tris, 60 mM SDS (sodium dodecly sulfate is a denaturing detergent; FW = 257), 1% powdered milk (FW = 49) , 1.3 M NaCl (FW = 45.5).

7) When making a buffer at a certain pH, one starts by dissolving the buffer into water and you read the pH is 5.2. What kind of substance would you add to get the pH to 7.2? And, if you wanted to make exactly 1L of this buffer, what order of what volumes would you add to not exceed the desired volume?

8) 1 OD260 unit of a double stranded DNA solution equals 50 µg /ml. You OD a solution and the spectrophotometer reads 0.057 but you are measuring a solution that is 3 µl DNA and 97 µl H2O. What is the concentration of the original DNA stock solution?.