An honours student needs to count the number of cells they have in a tube. They take an aliquot of the cells and dilute them 1:50 before loading 10 uL into a haemocytometer to perform a cell count. They count 4 quadrants and obtain the following counts for each quadrant: 12, 5, 17, 9.Which of the following statements is the most correct?Group of answer choicesThey should take the cells from the original flask, perform a new 1:5 dilution and repeat the cell countThe cells in the original flask are at a concentration of 5.4 x10^6 cells per mLThe cells in the original flask are at a concentration of 1.08 x 10^5 cells per mLThey should take the cells from the original flask, perform a new 1:100 dilution and repeat the cell count
Question
An honours student needs to count the number of cells they have in a tube. They take an aliquot of the cells and dilute them 1:50 before loading 10 uL into a haemocytometer to perform a cell count. They count 4 quadrants and obtain the following counts for each quadrant: 12, 5, 17, 9.Which of the following statements is the most correct?Group of answer choicesThey should take the cells from the original flask, perform a new 1:5 dilution and repeat the cell countThe cells in the original flask are at a concentration of 5.4 x10^6 cells per mLThe cells in the original flask are at a concentration of 1.08 x 10^5 cells per mLThey should take the cells from the original flask, perform a new 1:100 dilution and repeat the cell count
Solution
To answer this question, we first need to calculate the average cell count from the four quadrants.
The counts are: 12, 5, 17, 9.
The total count is 12 + 5 + 17 + 9 = 43 cells.
The average count is 43 cells / 4 quadrants = 10.75 cells per quadrant.
The volume of one square of a haemocytometer is 0.1 µL. Since we loaded 10 µL, we counted cells in 100 squares.
So, the concentration of cells in the diluted sample is 10.75 cells per quadrant * 10^4 quadrants per mL = 1.075 * 10^5 cells per mL.
However, this is the concentration in the diluted sample. The original sample was diluted 1:50, so the concentration in the original sample is 1.075 * 10^5 cells per mL * 50 = 5.375 * 10^6 cells per mL.
Therefore, the most correct statement is: "The cells in the original flask are at a concentration of 5.4 x10^6 cells per mL".
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