Demonstrating Osmosis Using Dialysis Membrane - Research Paper Example

? School The movement of water across the plasma membrane is called osmosis. Osmosis refers to the movement of water from a region of high water concentration to a region of low water concentration through a semi-permeable membrane. According Dr. Patlack and Watlers, understanding osmosis requires an examination of both solvent and solute behavior and, especially, the effect of solute on solvent behavior. Water is the universal solvent of life since a good majority of solvents dissolves in this solvent. The substance that can dissolve in water is known as a solute. Water can freely move across selectively permeable membrane but some solutes cannot. When the concentration of solute is different on both sides of the cell, a concentration gradient is created. If solutes are not able to pass through the cell, then water will move across the semi-membrane by osmosis to achieve equilibrium. The terms used to describe two solutions, which are separated by a membrane that is selectively impermeable are known as hypertonic, hypotonic, and isotonic. A hypotonic is a solution containing a lower concentration of solute than that found in the cell or opposing solution. A hypertonic is a solution containing a higher concentration of solute than that found in the cell or opposing solution. An isotonic solution is a solution with equal concentration of solutes in the solution and cell. If a cell is placed in a hypotonic solution; water will move into the cell from the opposing solution by osmosis and the cell will swell. The cell will eventually burst in case of red blood cell in a process called haemolysis. If a cell is placed in a hypertonic solution, water will move out of the cell to the opposing solution. The cell will reduce in volume. The cell will eventually shrink in case of red blood cell in a process crenation. If a cell is placed in a solution that is isotonic, there will be no movement in or out of the cell. If red blood cell is placed in a solution that is isotonic, the cell will not change in volume. Introduction The experiment demonstrates osmosis using dialysis membrane. A dialysis membrane is a permeable membrane that is selective, and it is made of cellulose. The dialysis membrane contains small pores that allow water and small solutes to flow in and out. It excludes large substances since they cannot pass through the small pores of the membrane. Thus, dialysis membrane is selectively permeable membrane and acts in this experiment as a cell. What is the effect of a changing sucrose concentration and water on a dialysis membrane? In the experiment, 5-dialysis tubing were each tied off at the bottom and later filled with sucrose solution. Each bag was also labeled so as not to confuse them. The bags were weighed and the weight recorded. After that, all the bags were placed in their respected solutions, the weight changes were then recorded in ten-minute intervals from the start time and at the end of the experiment. The aim of this experiment is to see the effects of osmosis through a permeable membrane that is selective using sucrose solution. This experiment is a replica of how osmosis takes place. The dialysis tubing serves as a permeable membrane, which osmosis will occur. Since cells are so small, this experiment serves as a replica in which osmosis is observed and recorded. It is expected that increasing the sucrose concentration and its percentage will increase the rate at which osmosis occurs in the experiment on the dialysis tubing. This will suggest that the more the concentrated sucrose solutions will be, the greater the rate of osmosis occurs and the lesser the sucrose concentration, the slower the rate of osmosis in the experiment. Materials Sucrose Solution, Dialysis Tubing, Syracuse dish filled with water, a String, five 500 ml Beakers, graduated cylinder Procedure 1. Take 5 bags of dialysis Tubing and soak them in Syracuse dish filled with water for 5 minutes. It is crucial to soak the dialysis tubing in water for the tubing to open. 2. Fold one end of each tube and tie it tightly with a string. Fill the bags with the following contents and tie the open end with string making sure that it does not leak: Bag 1 15 ml of water Bag 2 15 ml 20% sucrose Bag 3 15 ml 40% sucrose Bag 4 15 ml 60% sucrose Bag 5 15 ml of water Weigh each bag (this will be time zero). 3. Put bags 1-4 in four separate beakers each filled with 200 ml water 4. Place bag 5 in a beaker filled with 200 ml of 60% sucrose 5. Make sure to dry off bags with paper towel before weighing 6. At the end of the experiment, determine the change in weight of each bag. 7. Graph your results. The majority of the procedures for this experiment were performed as detailed for lab 04: Membranes as described in the spring 2013 BIO Laboratory Manual. Results Bag weight Bag 0 min 10 min 20 min 30 min 40 min 50 min 60 min Weight change 1 15.1 Grams 15.1 Grams 15.1 Grams 15.1 Grams 15.1 Grams 15.1 Grams 15.1 Grams 0 Grams 2 15.2 Grams 15.2 Grams 15.3 Grams 15.4 Grams 15.7 Grams 16.1 Grams 16.3 Grams 1.1 Grams 3 15.3 Grams 15.4 Grams 15.4 Grams 17.6 Grams 19.2 Grams 19.9 Grams 20.0 Grams 4.6 Grams 4 15.4 Grams 15.6 Grams 17.4 Grams 19.3 Grams 22.2 Grams 24.4 Grams 24.6 Grams 9.6 Grams 5 15.0 Grams 13.9 Grams 13.5 Grams 11.9 Grams 11.4 Grams 10.5 Grams 10.3 Grams - 4.7 Grams Observations Net movement of water in setup 1 When the experiment was done, Bag 1 was the only bag found to have no weight change. Its initial weight was 15.1 grams and the observed weight after one hour was 15.1 grams. It acted as the control experiment since there was limited movement of water from both contents. Net movement of water in setup 2 Bag 2 had a slight gain in weight, from its initial weight of 15.2 grams to 16.3 grams. Bag 2 containing 15 ml 20% sucrose withdrew water from the beaker and gained weight. Net movement of water in set up 3 Bag 3 also had a gain in weight, from its initial weight of 15.3 grams to 20.0 grams. Dialysis tubing with 15 ml 40% sucrose withdrew water from the beaker and gained weight. Net movement of water in setup 4 When the experiment was done, Bag 4 was the only bag to have a drastic weight increase. Its initial weight was 15.4 grams and the observed weight after one hour was 24.6 grams. Bag 4’s dialysis tubing containing 60% sucrose withdrew the highest water from the beaker, hence high weight gain. Net movement of water in setup 5 On the other hand, Bag 5 lost weight over time, starting out with 15.5 grams and ending at 10.3 grams. The beaker containing 60% sucrose solution, withdrew water from the dialysis tubing, hence weight loss. Discussion From the results taken, the concentrated solutions of sucrose seemed to draw the water towards it. Experiment was successful since sucrose solution created a concentration gradient hence osmosis takes place. The 10% sucrose solution contained sugars, which created a concentration gradient between the two solutions. If a bag contains 10% of sucrose solution and is placed in 100% of water, the highest concentration of sucrose is inside the bag. If the dialysis bag gains weight during the experiment, then water moved into the bag. If the dialysis bag loses weight during the experiment, then water moved out of the bag. Bag 1 placed in an isotonic solution since there was no change in weight. The two solutions were of the same concentration. Osmosis did not take place. It acted as a “control” experiment. Bag 4 has the maximum weight in the end primarily because it contained the highest percentage of sucrose solution within the membrane. Bag 4 had a stronger concentration of sucrose in its membrane, which draw water into the dialysis tubing from the hypotonic solution. The higher concentrations pulled the water out of the solution and into their membranes. Bag 2 & 3 had weight increase in the end because it contained the some percentage of sucrose solution within the membrane. The change in weight is due to the concentration of sucrose in the bag. Bag 5 was the only bag to have a radical weight decrease. Its initial weight was 15.1 grams and the observed weight after one hour was 10.4 grams. From the results taken, the concentrated solutions of sucrose in the beaker seemed to draw water from the dialysis Tubing towards the sucrose solution in the beaker. Bag 5 was placed in a hypertonic solution This is applicable in the real world situations with people who suffer from diabetes insipidus and mellitus. By raising or lowering, the blood sugar levels in their body. Diabetes Mellitus is caused by insufficient insulin when Istet of Langerhans present in the pancreas is destroyed. Sugar appears in urine because of increased blood sugar level. It even becomes dangerous when sugar level increases tremendously. Diabetes insipidus caused by a defect in secretion of vasopressin, secreted from the pituitary gland in the hypothalamus. Vasopressin reabsorbs water from distal tubules in the kidney controlling the concentration of urine. Its deficiency results to increased excretion of water through urine and even in low intake of water. Osmosis has been useful in these areas since through it researchers have come up with several medications that regulate the blood sugar levels of diabetic patients. References Dr. Patlak, J and Dr. Watters, C. (1997, 1999). Osmosis and Diffusion. Retrieved April 15, 2013 from: http://cr.middlebury.edu/biology/labbook/diffusion/pages/Osmosis11.html. University of Vermont and Middlebury College. Read More