1. How much 4X SDS-PAGE sample buffer do you need to add to 10 ul of a cell extract to run it out on an polyacrylamide gel?

2. You wish to plate out 5 x 10⁴ lymphocytes in a total of 2 ml for a focus forming assay. You dilute your cells 1:100 with crystal violet and count them with a hemocytometer. The average cell count is 25. What volume of cells would you add to what volume of medium to prepare your assay? Show your work!

3. An antibody to be used for Western blotting needs to be diluted 1:5,000 for optimum results. What volume of the antibody stock solution do you need to add to 100 ml of buffer to make the blotting solution? By the way, what other components should this buffer solution contain?

4. You have 20 ml of a protein sample in a 10% (w/v) suspension of sodium sulfate. How many rounds of dialysis (in a total volume of 1 liter) would be needed to reduce the salt concentration to 1 mg/ml or less?