Increasing the Molecular Weight of Glycol Molecules Increases the Time it Takes for Hemolysis to Occur in Ovine Blood Cells Victoria Sills Biology 1208 Section 10 Yubo Wang Abstract Membrane permeability is determined by the size and polarity of a molecule In Three different glycol molecules each containing a different molecular weight and complexity were used to determine if molecule weight and complexity affected hemolysis time in ovine red blood cells Ovine blood was mixed with one of the three glycol solutions and held up to a slit lamp apparatus until hemolysis had occurred when the wire was visible Triethylene the glycol substance with the highest molecular weight and complexity had a significantly higher hemolysis time than the other glycol solutions with a lower molecular weight and less complexity The glycol molecule with the lowest molecular weight had the fastest rate of hemolysis The diffusion rate of heavier more complex solutions is higher than that of lighter less complex solutions Introduction Hemolysis is the process of what happens to a red blood cell when placed in a hypotonic solution Because the solution is hypotonic the high concentration of water in the solution will move down its concentration gradient into the cell with the high concentration of solute The water rushes into the cell causing it to swell and burst Reece The rate of hemolysis changes with the solution the red blood cells are placed into Rate of diffusion hemolysis in this case depends on many factors such as polarity size and shape because the membrane is selectively permeable Our null hypothesis we formulated states that changing the molecular weight of a glycol molecule will not change the time it takes for hemolysis to occur Our alternative hypothesis we formulated states that if you change the molecular weight of a glycol group then the time it take hemolysis to occur will also change Before beginning this experiment we predicted that the glycol solution with the highest molecular weight triethylene will have the highest hemolysis time This experiment was carried out to determine molecular weight s role in hemolysis time in ovine red blood cells This experiment allows us to better understand membrane permeability through different molecules ranging in weight and complexity Materials and Methods To begin the experiment obtain 9 test tubes and label them 1 9 For our three glycol molecules we used ethylene glycol with a molecular weight of 62 07 Daltons diethylene glycol with a molecular weight of 106 10 Daltons and triethylene glycol with a molecular weight of 150 17 Daltons Next we pipetted 4 ml of ethylene glycol into test tubes 1 3 4 ml of diethylene glycol in test tubes 4 6 and 4 ml of triethylene glycol in test tubes 7 9 The rate of hemolysis was then measured by placing 1 ml of 2 whole ovine blood into test tube 1 After pouring in the blood solution immediately start the timer and cover the test tube with Parafilm Quickly invert the tube to mix Immediately hold the test tube up to the slit lamp apparatus The slit lamp method consists of a diffuse light source positioned behind a piece of cardboard with a hole in which a black thread is suspended Wischusen et al 2012 Once the thread becomes at least 75 visible through the solution the red blood cells have been hemolyzed and the timer should be stopped Record the hemolysis time Once completed repeat the process for the eight remaining tubes Each of the three glycol solutions has three trials to get more accurate and consistent results Results 40 35 30 25 20 15 10 5 0 i s e m T s i s y l o m e H Hemolysis Time vs Different Glycols Series1 Ethylene Diethylene Triethylene Different Glycols Figure 1 The rate of hemolysis in ovine red blood cells when placed in three different glycol solutions The bar graph demonstrates the relationship between molecular weight and hemolysis time Each glycol solution has a different molecular weight Ethylene with the lowest molecular weight of 62 07 Daltons had an average hemolysis time of 9 15 seconds with a standard deviation of 0 0794s Next diethylene with a molecular weight of 106 12 Daltons had an average hemolysis time of 16 55 seconds with a standard deviation of 1 0889s Having the highest molecular weight of 150 17 Daltons triethylene had an average hemolysis time of 34 23 seconds with a standard deviation of 1 2401s Results Continued The main trend in our results as shown in the graph below was the direct relationship between molecular weight of the glycol molecule and hemolysis time As the molecular weight of a glycol molecule increased the hemolysis time significantly increased as well Ethylene with the lowest molecular weight of 62 07 Daltons took 9 15 seconds to hemolyze While diethylene with a molecular weight of 106 12 Daltons 44 05 Daltons greater than ethylene took 16 55 seconds to hemolyze 7 4 seconds longer than ethylene Finally triethylene with a molecular weight of 150 17 Daltons 88 1 Daltons bigger than ethylene and 44 05 Daltons bigger than diethylene took 34 23 seconds to hemolyze 25 08 seconds longer than ethylene and 17 68 seconds longer than diethylene Discussion The experiment was carried out to help develop an understanding of diffusion and membrane permeability Membrane permeability depends on the polarity size and the shape of the molecule trying to cross the membrane Our results demonstrated the more complex heavier the molecule is the longer the molecule takes to diffuse across the membrane or hemolyze After analyzing the results of this experiment it is clear that the results best support the alternative hypothesis The alternative hypothesis stated that if the molecular weight of a glycol molecule were changed then the time it takes hemolysis to occur would also change Therefore the null hypothesis should be rejected because our results demonstrated a significant change in hemolysis time when the molecular weight of a glycol molecule was changed Hemolysis time increased as the molecular weight of the glycol molecule increased In accordance with our findings triethylene had the highest hemolysis time because it has the highest molecular weight and the most complexity Diethylene had the second highest hemolysis time because it has a molecular weight in between triethylene and ethylene Finally ethylene had the fastest rate of hemolysis because it has the smallest molecular weight Literature Cited Education 2011 Print Reece Jane B and Neil A Campbell Biology Boston Benjamin