Lab Report Of An Experiment To Find Out the Example of Passive Transport Processes in Cells - Essay Example

? of Affiliation LAB REPORT OF AN EXPERIMENT TO FIND OUT THE PROCESS OF PASSIVE TRANSPORT IN CELLS Introduction: A cell membrane is one of the most important parts of a cell. It is the outer layer that covers the cells of animals including man. This membrane is described as selectively permeable - a factor that contributes to its ability to control the substances that will pass across it into or out of the cell. This unique characteristic of the cell membrane makes it suitable for the processes involved in passive transport (Rondell, & DaufiI, 2007). Passive transport is an important process that occurs across this membrane and involves the movement of substances in and out of the cell without using any energy. This movement is facilitated entirely by the molecules’ inherent kinetic energy (Raber, 2000). Examples of passive processes include osmosis and diffusion. In this report, I consider an experiment carried out in a laboratory to demonstrate the process of osmosis is it occurs in across the cell membrane. Definition of terms Hypotonic solution- this refers to a situation where the solute molecules concentration outside the cell is lower when compared to the concentration of solutes molecules within the cell. Hypertonic solution- solute molecules concentration outside the cell is higher when compared to the solute molecule concentration within the cell. Isotonic- a situation where the solute molecules concentration within and outside the cell is equal. Purpose: The aim of this lab report is to detail the process of passive transport: osmosis and diffusion in mock-up membrane system. This experiment will detail how molecules in a solution travel from places where they are in high concentration to areas where their concentration is low. The mock-up membrane is made from dialysis tubing. Hypothesis: i. The Viking tubing will increase in mass in all instances of the experiment, showing that osmosis occurred. ii. The color of the water in the beaker will change implying the movement of solutes from the Viking tubing into the beaker Materials i. Dialysis tubing – 2.5 cm ii. Distilled water iii. 15 percent glucose solution iv. 1precent starch solution v. Glucose test strip vi. Lugol’s iodine solution Procedure: 1) Get 30 cm dialysis tubing that has been soaked in water for some period. Fasten one of its ends to create a bag. Rub the other end between your fingers to separate the edges and cause it to open. 2) Put 15ml of the 1% starch and 15% glucose solution in the bag. Fasten off the remaining open end, making an allowance for the content expansion. Document the weight and color of the solution at the beginning of the experiment in a data table. 3) Take the glucose test strip and use it to investigate the presence of glucose in the 1% starch 15% glucose solution. Use the data table to record your finding. 4) Take a 250ml beaker, fill it with distilled water, and add about 4 ml Logol’s solution then use the data table to record the resultant color of the solution. Analyze the solution to find the presence of glucose and record the findings in the data table. 5) Submerge the bag into the solution in the beaker. 6) Give the set-up a period of about 30 minutes to settle or until color change in the beaker or the bag is evident. Document the last color of the solution within the bag, and the color of the solution within the beaker in the data table. Take note of the bag final Weight and document it to in the data table. 7) Use the test tape to analyze the solution in the bag and the one in the beaker for glucose presence and record the findings in the data table. Data table ITEM INITIAL CONTENT INITIAL COLOR INITIAL MASS FINALCONTENT FINAL COLOR FINAL MASS Dialysis bag-(1st experiment) Starch/glucose solution white 30g Starch /glucose solution purple 34g Beaker – (1st experiment ) H2O/Iodine Yellow H2O/Iodine/glucose yellow Dialysis bag-(2nd experiment) Starch/glucose solution Milky white 24g Starch /glucose solution Blue-purple 26g Beaker – (2nd experiment H2O/Iodine Gold H2O/Iodine/glucose Gold Dialysis bag-(3rd experiment) Starch/glucose solution white 33g Starch /glucose solution Purple 35g Beaker – (3rd experiment ) H2O/Iodine yellow H2O/Iodine/glucose yellow Results The result data indicates that in each single instance of the experiment the bag increased in mass after 30 minutes. In addition, the result show that starch within the bag changed to take a blue color. Evaluation using the test strip depicted glucose presence in the water/ Iodine solution. Analysis/ Discussion As detailed above diffusion refers to the process by which particles move from an area where they are in high concentration to an area where their concentration is low. On the other hand, osmosis is defined as diffusion of water in and out of a selectively permeable membrane. Such is the case that the selectively permeable membrane will only allow water and several other small particles to diffuse through osmosis. Dialysis tubing and the cell membrane are alike in the way they operate (Sperelakis, 2003). As shown by this experiment, the cell is expected to lose water through osmosis when put in an environment having a higher water concentration when compared to the concentration in the cell. The solution within the dialysis tubing was highly concentrated in terms of solutes (i.e. 1% starch/15percentage glucose) when compared to the concentration of the distilled water and iodine (H2O/ iodine) solution. The beaker content characterizes hypotonic solution, “one in which the concentration of dissolved substances is lower than the concentration inside the dialysis tubing.” Due to osmosis, the water moved into the dialysis bag via the dialysis tubing. The change in mass of the three bags proved the movement of water into them. On the other hand, the dialysis bag represented hypertonic solution since its concentration with regard to dissolved substances exceeded the concentration of its surrounding environment. Due to the process of osmosis, the glucose moved via dialysis tubing into the beaker. At the end of the experiment, the test strip analysis indicated that glucose had moved out of the tubing. Application of Passive transport In plants, osmosis helps in water absorption from the soil that is usually carried out by young roots. Here the concentration of water in the soil is greater when compared to water concentration in the root hairs, a factor that causes the water to move into the roots. This process repeats itself within the plants cells until the water is able to flow up to the leaves. In animals, osmosis plays a significant role in maintaining equilibrium between the cell inward environment and its surrounding. Such is the case that is this process does not occur cells might bulge due to much water and burst or shrink due to loss of water. On the other side, diffusion is evident when plants take in nutrients from the soil. Such is the case that nutrients in the soil are in high concentration than within the plant roots. Consequently, the nutrients will move into the roots and then up the plant cells until it get to the leaves. In addition, the absorption of carbon dioxide by plants in the process of making food (photosynthesis) uses the process of diffusion. In animals, diffusion takes place in small intestine, lungs and even kidney. First, in the small intestine nutrients from food eaten is absorbed into the blood stream. The second application regards the lungs where oxygen is absorbed and passed into the blood stream while carbon dioxide is expelled from the blood stream to the outside through the nose. Lastly, in the kidney, excess salt is absorbed and later expelled out of the body as urine. Conclusion Through the process of osmosis, water was able to move from the beaker where it was in high concentration into the dialysis tube where its concentration was low. On the other hand, there the process of diffusion worked to realize the movement of glucose from the dialysis bag where the concentration was high into the beaker where its concentration was low. Therefore, the experiment successfully showed the process of passive transport across the semi-permeable membrane of cells. References Raber, O. (2000). Principles of plant physiology. New York: Macmillan. Rondell, P., & DaufiI, L. (2007). Diffusions and osmosis. New York, NY: John Wiley and Sons. Sperelakis, N. (2003). Cell physiology source book. San Diego: Academic Press. Read More