2. Answer the following questions a. You have a flask of cells in culture. The d
ID: 255901 • Letter: 2
Question
2. Answer the following questions a. You have a flask of cells in culture. The density of cells in the flask is 1.52 x 106 cells/mL. What volume of this culture would you need in order to have 500,000 total cells? b. You add 157 ?L of a cell culture that is 2.9 × 106 cells/mL to a new flask. How many cells are in the new flask? If you bring the flask up to a total volume of 10 mL, what is the cell density? C. You add 334 ? L of a cell culture that is 1.21 × 105 cells/mL to a new flask and bring the total volume up to 5 mL. What is the cell density of your new cell culture? d. To calculate a dilution factor, divide the final volume by the initial volume (Vt/Vi). If you took 100 ?L of cell suspension and added 100 ?L H2O, what is the dilution factor? (Hint: Vr= 200 ??,Vi = 100 ?L.) e. What is the dilution factor if you add 75 ?L of water to 25 ?L of cell suspension? f. You took 1.0 mL of cell culture, spun it down in a centrifuge removed the medium and brought the cell pellet up to 100 ?L with PBS. What is the dilution factor? g. On a hemacytometer you counted a total 404 cells in four of the quadrant squares. The dilution factor is 2. What is the density of the original culture?Explanation / Answer
ANSWER 2.
Answer a.
We use Unitary Method:
1.52 * 106 cells are there in 1 mL
Therefore, 1 cell is there in 1 / (1.52 * 106) mL
Therefore, 500,000 cells are there in 500,000 / (1.52 * 106) = 0.3289 mL
Answer b.
We use Unitary Method:
1 mL = 1000 uL
1000 uL contains 2.9 * 106 cells
157 uL contains 2.9 * 106 * (157/1000) cells = 455,300 cells
In a total volume of 10 mL, the cell density would be 455,300 cells / 10 mL
or, 45,530 cells/mL
Answer c.
We use Unitary Method:
1 mL = 1000 uL
1000 uL contains 1.21 * 105 cells
334 uL contains 1.21 * 105 * (334/1000) cells = 40,414 cells
In a total volume of 5 mL, the cell density would be 40,414 cells / 5 mL
or, 8,082.8 cells/mL
Answer d.
Final volume Vf = 200 uL
Initial volume Vi = 100 uL
Dilution Factor = (Vf/Vi) = 200/100 = 2
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