Question

4. A student has taken 1 ml of his cell suspension at 8.5 x 104 cells/ml into 4 mls of media in order to plate them in a new culture vessel. What is the concentration of cells at the start of the new culture? (1 point) 5. A student has a cell suspension of 1.5 X 109 cells/ml. How is she going to prepare 5 separate cultures of 5 mls each at the concentration of 1000 cells/ml each? (1 point)
PLEASE HELP SOLVE BOTH QUESTIONS, show all work and circle answers thanks !

Answer 1

4. The student has taken 1 mL of suspension having the concentration 8.5 x 10⁴ cells / ml

This means 1 mL of this suspension contains 8.5 x 10⁴ cells

The students taken this 1 mL suspension into 4 mL of media.

Thus the volume of final solution is 5 mL

Now 8.5 x 10⁴ cells are present in 5 mL of solution.

Therefore the concentration of cells at the start of the new culture is 8.5 x 10⁴ cells / 5 mL = 1.7 x 10⁴ cells / mL

Thus the required concentration of cells at the start of new culture is 1.7 x 10⁴ cells / mL

5. The problem can be solved using the dilution law

The initial concentration (N₁) is 1.5 x 10⁶ cells / mL

The final concentration (N₂) should be 1000 cells / mL

The final volume (V₂₎ given is 5 mL

We need to find out initial volume (V₁)

From the dilution law,

N₁V₁ = N₂V₂

V₁ = (1000 cells / mL x 5 mL) / 1.5 x 10⁶ = 0.033 mL

Thus the volume of cell suspension to be taken is 0.033 mL

The remaining component in the cell culture is media = 5 mL - 0.033 mL = 4.967 mL

Thus by taking 4.967 mL of media and 0.033 mL of cell suspension in 5 different vessels, the student can prepare 5 different cell cultures of 5 mL each at a concentration of 1000 cells/mL