3. A mixture of proteins will be separated on a gel filtration column. The first peak elutes in 12 ml from the column, and the last peak elutes in 42 ml. The flow rate in the column is 1.5 ml/minute. The column diameter is 1.0 cm, and the height is 60 cm. Protein MW Кр 1 NaCl 58.44 aprotinin 6500 0.69 43,000 75,000 2,000,000 ovalbumin 0.43 Conalbumin 0.35 Blue Dextran

1. How many mL of sterile water must be added to make the preparation isotonic? 2. How many mL of another isotonic solution must be added to make the final volume of the solution?

CFU Remember: = Number of Colonies Counted x ml. 1 Dilution Factor # of ml. plated out Treat grams dirt or organic material as follows: 1 gram 1 cubic centimeter (1 cm) =1 mL. %3D CFU V;D;=V,D2 OCD = Volume x Dilution V=Volume D=dilution 1. Calculate the CFU/ml of a urine sample if 49 E. coli colonies were counted on NA when 50 microliters were plated on the NA plate from a 10-6 dilution tube. 2. Plating 0.1 mL of a sample diluted by a factor of 10 produced 43 colonies. What was the original concentration (CFU/ml) in the sample? 3. You have inoculated 100 microliters of a sample diluted by a factor of 103 on a NA plate. After incubation, you count 58 colonies. What was the original concentration (CFU/ml) in the sample?

#21