In the hemolysis experiment, three treatment solutions namely propanol, propaned

Question

In the hemolysis experiment, three treatment solutions namely propanol, propanediol and propanetriol were used to determine how polarity affected time to hemolysis. Ethylene glycol, diethylene glycol, and triethylene glycol were used to determine how molecular weight affected time to hemolysis. Propanol has a polarityof 1 (OHgroup) and a molecular weight of 60 g/mol. Propanediol has polarity of 2 and a molecular weight of 76 g/mol. Propanetriol has a polarity of 3 and a molecular weight of 92 g/mol. So in these three cases, boht polarity and molecular weight are increasing. So can you be sure that it was increasing polarity and not increasing molecular weight which led to increased hemolysis time in the case of the propanols? What would your experimental setup be to investigate this?

Explanation / Answer

We examined the effect the concentration of diethylene glycol had on the lysis timeof sheep red blood cells. In order to test this, we placed a set amount of sheep red blood cells in diethylene glycol solutions in test tubes. We then determined the hemolysis time by recording the number of seconds it took for the solution in the test tube to turn clear, indicating that all the red blood cells in the solution had lysed. To determine the time at which the solution turned clear, we held the test tube containing the solution in front of a hole in a surface with a line running through the hole. We assumed the solution turned clear when the line became visible through the red blood cell solution.

For polarity, we placed sheep red blood cells in a solution with slightly polar solutes (butanol) and in a solution with slightly more polar solutes (1,3 propanedol). We then timed the hemolysis time by recording the amount of seconds it took for the solution in the test tube to turn clear, indicating that all the red blood cells in the solution had lysed.

For size, we examined the effect the size of molecules had on the lysis time of red blood cells. In order to test this, we placed a set amount of sheep red blood cells in a solution with various sized molecules (ethylene glycol, diethylene glycol, triethylene glycol). We then timed the hemolysis time by recording the amount of seconds it took for the solution in the test tube to turn clear, indicating that all the red blood cells in the solution had lysed.

Hypothesis: I hypothesized that the concentration would affect the rate of diffusion of red blood cells. Specifically, an increase in concentration would cause a decrease in the rate of diffusion.

Rationale: Diethylene glycol is the solute that passes through red blood cell membranes by passive diffusion. Diffusion of diethlyene glycol into the red blood cell will in turn cause water in the solution to move into the red blood cell by osmosis. At a certain point, the pressure of water inside the red blood cell will overcome the strength of the red blood cell membrane, thereby causing the red blood cell to swell and lyse. Greater amounts of solute inside the cell should cause water to move into the cell faster, causing the red blood cells to lyse faster.

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