Varying the concentration of solutions
Experiment 3: Effect of graded series of hypotonic saline solutions
What factors & particle properties determine how quickly substances move across an RBC membrane to cause the RBC to swell and lyse?
We will explore that in three Experiments 3, 4 and 5.
In Experiment 3, which you will do on this page, we will expand what we did in Experiments 1 and 2, using a range of saline concentrations.
Recall that in Experiment 1 we used 100% Physiological saline and Distilled water (i.e., 0% Physiological Saline). We found that lysis was instantaneous in the second solution and never happened in the first solution.
In Experiment 2 we used 50% Physiological Saline (hypotonic saline) and found lysis occurred with a time value between instantaneous and never! Not very satisfactory science if all we test and see is "Never", "Immediate", and "Somewhere-in-between"! We have no idea what is the shape of the curve between % Physiological saline and Time for lysis!
So now we are going to create a series of other hypotonic saline solutions between 0% Physiological saline (Distilled water) and 100% Physiological saline, and test for lysis. This should give us a series of values that allows us to draw a curve for the relationship between % Physiological saline and Time for lysis.
That is what we will do in Experiment 3, as you can see in the Table below
- Using the proportions shown in the table below, mix a solution containing both distilled water and physiological saline in your test tube.
- Add some blood to your test tube and time how long it takes for the mixture to clear up enough to see the light.
- Record the time taken for your solution in the table below.
- Repeat for other mixtures and record your results in the table.
Note: If lysis doesn't occur within 90 seconds, we assume it will never occur, and you should enter a value of 90 seconds for that trial.
|Distilled water volume (mL)||Isotonic saline volume (mL)||End product||Haemolysis time (s)|