A bacterial sample loaded onto a hemocytometer.You count each of the four corner

Question

A bacterial sample loaded onto a hemocytometer.You count each of the four corners. Your results are listed below. 3. Square Top Left Top Right Count 45 20 42 60 Bottom Left Bottom Right What is the Mean of your counts? 4. What is the concentration of bacteria loaded on the hemocytometer? Write down your calculations. The sample loaded on the hemocytometer is actually a dilution of the sample you are testing. You diluted the sample by taking 0.1 mL of sample and adding it to 0.9 mL of buffer before loading the hemocytometer. 5. What is the concentration of bacteria in the original sample?

Explanation / Answer

Answer 3: Mean cell count = (45+20+42+60)/4 = 41.75 (41 approx.)

Answer 4: Usually minimum 5µl is loaded in hemocytometer and capacity of one chamber counted above is 0.1mm3 = 0.1 µl

Therefore if 0.1 µl contains an average of 41.75 (41 approx.) cells, total cells loaded will be around 41*50=2050 (approximate cells loaded in hemocytometer).

Answer 5:

Number of cells/ml = Average number of cell per square x Dilution Factor x 104

                                    = 41*10*104

                                    = 41*105

                                                = 4.1*106

(0.1ml original sample contains 4.1 million cells, on the bases of it, number of cells can be calculated for total volume)

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