The Occurrence of Osmosis and Diffusion in Artificial
The first part concentrated on the placing potato cylinders in different sucrose concentrations for a period of time. This part was conducted to see if the potato cylinders would gain weight or lose weight because of osmosis. The second part was conducted to see if a dialysis bag, filled with sodium sulfate and starch solution and placed in an albumin/glucose solution, would contain albumin/glucose from the outside or the albumin/glucose solution would contain any sodium sulfate/starch from the inside. The first part of this experiment there is a relationship between the amount of sucrose concentration and final mass.
As the sucrose concentration increased the mass of the potatoes decreased. This is a result of the sucrose molecules not being small enough to pass into the membrane of the potato cylinders, but the water was able to change to a different concentration gradient. As the sucrose amount increased the free water molecules decreased, which as a result did not allow the water molecules to enter the potato cylinders. On the contrary, no diffusion of solutes occurred in part two of this experiment. Osmosis, on the other hand, did occur. Water moved into the dialysis bag, thus increasing the bag’s weight.
Diffusion did not occur because of the size of the pores in the dialysis bag. The solute molecules were too large to diffuse while the water was able to diffuse because it was smaller. The results gathered for this experiment report the direct factors that affect osmosis and diffusion. The concentration of solute was the factor that affected first part of this experiment. The molecule and pore size were the factors that affected the second part of this experiment. Introduction This experiment was conducted to learn the processes of diffusion and osmosis.
The conductor learned the process through two experiments. The conductor then measured the osmosis of water in and out of the cells of the potato. The first experiment was conducted using an artificial system. In this experiment the conductor measured the diffusion of solutes and osmosis of water in and out of the dialysis tube. This first part of the experiment was the artificial system. Diffusion is defined as the net movement of like molecules or ions from an area of high concentration to an area of low concentration (Keith, Messing, & Schmitt, 2010). Diffusion is a process that requires no energy.
The difference in the concentration of the adjacent regions in the process of diffusion is called the concentration gradient. The concentration gradient can be used to see where the most potential energy. The potential energy is stored in the molecules before they move (High Concentration). The concentration gradient can also be used to locate the kinetic energy of diffusion. The kinetic energy is released when the molecules move (Low Concentration). Molecule always moves down a concentration gradient (High to Low). High Concentration High Concentration * Low Concentration Low Concentration
Water diffuses just like any other substance. Water will move from areas of high concentration to low concentration. The water moves from high concentration to low concentration when there is a difference in the solute concentration in the membrane or when the solute molecules are too large to move across the membrane (Keith et al,. 2010). Some examples of this can be a molecule is not small enough to pass through the membrane or if a molecule is charged. When this occurs most of the solute is now unable to diffuse to the other side the water molecules are now in the shells of the solute.
The water is now not available for diffusion. In this case the water concentration is low. On the other side of the concentration gradient there is little or no diffusible solute. The water is “free”, thus allowing the water to move from areas of low solute concentration to an area of high solute concentration. Osmosis can affect blood cells based on the level of the solute. If a red blood cell were placed in a beaker of seawater, the red blood cell would shrink. This shrinking of the red blood cell happens because the seawater has more solute that the cytosol of the red blood cells.
This situation causes the water to move out of the red blood cells. Due to the fact that the red blood cell shrunk this environment is considered hypertonic. When a red blood cell is dropped into a beaker of distilled water solution the red blood cell will burst. The reason the red blood cell exploded was because the cytosol has more solute than the distilled water and the distilled water move into red blood cell. This environment is called hypotonic. If a red blood cell is dropped into a beaker of the same solute concentration solution as the cytosol, the water will move in and out of the cell.
This creates no net movement of water. The cell remains stable and does not change in size. This environment is labeled as isotonic. There are a plethora of factors that determine the rate of the movement of water around the membrane. A factor in the determination is the solute concentration across the membrane. When the solute concentration has a difference across the membrane, then water will move across the membrane. This will make water move quicker. This lab focuses on study of osmosis and diffusion in the dialysis bag, which is semipermeable.
The dialysis bag contains all very small opening in the surface. These openings or pores vary in size. Due to the fact that water molecules are much smaller than biological macromolecules, this experiment will feature both osmosis and water and diffusion. In comparison to the real cell membrane the cell membrane is more selective on the particle that pass through. If the selectivity of the dialysis tube is not considered then this is a good represent of the cell membrane. (Keith et al,. 2010) Hypothesis Part I: Water Potential (Potato core in different concentrations of sucrose solutions)
Ho: The weights of the potato cylinders will not change after contact with solution for a period of one hour. Ha: There will be a change in the weight of the potato slices after being in contact with solution for a period of one hour. Part II: Simultaneous Osmosis and Diffusion: (dialysis tubing experiment) Ho: Diffusion or osmosis will not take place in the dialysis bag. Ha: Diffusion or osmosis will change the contents of the bag and the weight. Materials and Methods Part I: Water Potential In this experiment the focus on osmosis and diffusion in the potato cylinders.
This experiment requires the following material, a potato, 7 beakers or small cups with some of one of following: 2 M sucrose, 4 M sucrose, . 4M sucrose, . 6M sucrose, . 8M sucrose, 1m sucrose, distilled water, an unknown solution. Another requirement for this lab is a cork borer to cut the potato into 28 cylinders. Place 50 mL of each of the different sucrose solutions in separate 100 mL beakers, as well as the distilled water, and unknown solution. Next, use the cork borer to create 28 potato cylinders from the potato. Cut the ends to remove the skin.
Make sure 28 cylinders are made so that four can be placed in each of the beakers of sucrose solution. After the cylinders have been obtained, place the cylinders into seven groups of four. Weigh each of the seven groups and record the weights in table 1. take the cylinder groups and drop each group in a beaker of sucrose solution, one group to a beaker. Leave the potato cylinder in the solutions for one hour at room temperature. After the time has elapsed, remove the potato cylinders and gently record the weights of each group. Record the findings in table 1.
After obtaining the final weights, calculate the percentage change with the following equation: % change= Start mass-Final mass/Start mass ? 100% Record your percent change in table one, as well. Obtain the data from other groups and place in table 2. The control group in this experiment is the group of potato cylinders in the distilled water. The experimental groups are the potato cylinders in the different sucrose solutions and unknown solution.. The independent variable in this experiment is the sucrose concentration. The dependent variable is the masses of each of the groups of potato cylinder.
Part II: Simultaneous Osmosis and Diffusion This part of the experiment utilizes the dialysis bag as an artificial system. The required materials for the first part of the experiment are a 20cm long dialysis tubing, 8 test tubes, beakers, starch (MW>100,000 Daltons) and sodium sulfate (Na2So3, MW= 142 Daltons) solution, solution containing albumin (MW~64,000 Daltons) and glucose (MW=180 Daltons), distilled water for washing, a “dip and read” strip for glucose, a “dip and read” strip for protein, 2% barium chloride solution, and iodine solution. Note: When handling the dialysis tubing wear glvoes.
The dirt and oil from human hands will potentially clog the pores. At your workstation take the 20cm dialysis tubing and soak it in a beaker of distilled water. Flush the insdide of the tubing and make sure to squeeze out the excess water. After all the excess water has been removed tie or fold and clip one end of the dialysis tube, to create a pouch. Next, add 3 mL of the starch and sodium sulfate solution in the dialysis bag and tie or fold and clip the other end to close the pouch. After tying off the dialysis bag, take the bag and wash it in distilled water, carefully blot dry so not to puncture the bag and weight it.
Record the weight as “starting weight”. To each of four test tubes, labeled “bag start”, add 1 mL of the starch sodium sulfate solution. Take the bag and place it in a beaker containing albumin and glucose solution. Be sure to completely cover the bag. Keep the bag in the solution for 120 minutes. At 15-minute intervals gently swirl the bag inside the beaker containing the albumin/glucose solution. After the 120 minutes have passed, take four 1 mL samples of the albumin/glucose solution that was in the beaker and add the samples to four test tubes labeled “solution end”.
Next, remove the bag from the beaker of albumin/glucose solution, and rinse the bag with distilled water. Blot the bag dry, carefully, after weight the bag. Record the weight as end weight”. Open the bag and empty the contents into a beaker. Take four 1 mL samples of the dialysis bag’s starch/ sodium sulfate solution and add them to four test tubes labeled “bag end”. Next test the different materials that diffused into the bag. In order to test for glucose, dip a glucose “dip and read” strip in the first tube from each of the group of samples, “bag start, bag end, solution start, and solution end”.
At the end of the strip there is a small pad, indicator, when it changes color match the color with the color code on the side of the bottle. If the indicator turns a positive color then there is glucose in your sample. In order to test for sodium sulfate in the solution and bag samples add 10 drops of 2% barium chloride(BaCl2) to the second test tube from each of the group samples,“bag start, bag end, solution start, and solution end”. If there is a presence of sodium sulfate in the solution the sulfate ion will precipitate with the barium ion, thus forming white particles.
To test for protein, dip a protein “dip and read” strip into each test tube three from the group samples. The indicator at the end of the strip will change color if there is a presence of protein in the solutions. To test for starch in the solutions add a few drops of iodine solution to each of the fourth test tubes in each of the group samples. If the starch is present in the solutions the solution will turn light brown. If there is no starch in the solution the solution will turn dark brown. In this experiments there are two control groups, “solution start” and “bag start” test tube.