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Maria Faye Stephanie Cantago                                                                      January29, 2018Zaham ZaragozaExercise 1MOVEMENTTHROUGH MEMBRANESABSTRACTThe transport ofmolecules inside and outside of the cell requires a complicated system to be asefficient as possible. This transport system comprises the passive and activetransport of molecules. In the experiment, the type of transport tackled is thepassive transport without the use of energy or ATP.

Some of the results followedthe standard results of the experiment, with the exception of some tests in thedialysis which maybe due to the remaining fate tissues inside the dialyzingmembrane. This is also true to the human body’s transport system which becomesless efficient when it is blocked by fats. In conclusion, cell to celltransport is very important for the continuous function of the cells, tissues,organs and the body in general.RESULTSAND DISCUSSIONI.             DiffusionA.    Diffusionof gas in a GasAccording toGraham (1829), equal volumes of different gases diffuse in very unequal timeswhich also has an inverse relation to the specific gravity of the gas and itsdensity.

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Furthermore, the vapor or gas will be propagated to any distance, byexchanging positions with a train of particles of air, according to the law of diffusion.The length, to which this diffusion proceeds, in a confined portion of air, islimited by a property of vapor, namely, that the particles of any vaporcondense when they approximate within a certain distance (Wisniak, 2013). Distance Time Rate 1 m 18.3 secs 0.054 m/sec 2 m 1 min 39 secs 0.020 m/sec 3 m 2 mins 5 secs 0.024 m/sec 4 m 3 mins 38 secs 0.018 m/sec 5 m 4 mins 56 secs 0.

017 m/sec Table1. Rate of diffusion of perfume in a close room.            The material used in the experimentis a perfume placed in a petri dish and was left to evaporate and diffuse in aclose room. The different distances covered by the experimenters were one tofive meters. The result was obtained by how long will the gas take to diffusein the air and reach the experimenters olfactory system. When the perfumeevaporated and diffused, there was no outside air to help it spread fasteracross the room.

The farther the student was from the perfume, that longer thetime it took for the student to smell the perfume (Table 1). As the moleculesof the perfume slowly travel across the room, it moves randomly, bumping theair molecules in the room and made the travel of the gas to the experimentsolfactory system to be longer.B.    Diffusionof a Solid in a Colloidal SolutionThe diffusion of solids has the slowestrate, however, this depends on the interaction of the solid to its medium (“Whydoes diffusion take place”, 2016). The diffusion rate of solid is also affectedby the weight of the solid.

As the molecular weight increases, rate ofdiffusion decreases. Another thing that can affect the rate of diffusion is thetemperature (“Why does diffusion take place”, 2016). As the temperatureincreases, the rate of diffusion also increases.        Figure 1.

Graph of the diffusion rate of solidsin a colloidal solution.Table 2. Diffusion rate of different solids in a colloidalsolution.

Substance Rate of Diffusion Potassium permanganate (158g/mol) 0.402 mm/ min Methylene blue (327g/mol) 0.016 mm/ min Potassium dichromate (294g/mol) 0.225 mm/ min Inthe experiment, potassium permanganate, with a molecular weight of 158 g/mole,has the highest average rate of diffusion. This is followed by potassiumdichromate, having a molecular weight off 294 g/mole, and methylene blue, with374 g/mole molecular weight. The trend indicates that the lower the molecularweight of a substance, the faster it diffuses in the agar (Table 2 and Fig.

1).Thus, confirming that the rate of diffusion of a substance is affected by itsmolecular weight.C.   Diffusionof a Solid in a Liquid        The diffusion of solid in the liquidmedium involves a separation of solute from the surface of the solid and thedisintegration of the solute molecules into the liquid phase (Hsu and Liu,1993). The diffusion rate of solid in liquid is relatively faster compared tothe diffusion of solid in a colloidal surface.

Other factors that may affectthe diffusion rate of solid are temperature, mass and size of the particle. ­­­­Figure 2. Potassium permanganate crystal slowly diffusing inthe container        In the experiment, potassiumpermanganate was used as the solid that diffused in the liquid medium which iswater. The potassium permanganate crystal slowly dissolved in the bottom of thebeaker and starts to diffuse.

This process is called dissolution which is dueto the diffusion of the solid particles. After 30 minutes, the potassiumpermanganate, the purple dye (Fig. 2), finally covered the bottom part of thebeaker. Furthermore, the size of the potassium permanganate crystals alsoaffected the rate of the diffusion since the larger the surface area, thefaster the diffusion rate (“Study of Diffusion of Solids in Liquids”, 2015).II.           Osmosis         Osmosis is a type of passive transportof water molecules across a semi-permeable membrane following the concentrationgradient of the solute.

It can happen during a) two solutions are separated bya water permeable membrane but impermeable to at least one of the solutes inthe solution and b) the total concentration of impermeable solutes between thetwo solutions inside and outside the membrane is different (Finkler, n.d.).   Table 3.

Weight of thediffusing membranes with NaCl and distilled water every 5 minutes. TIme NaCl filled membrane in water solution Water filled membrane in NaCl solution 0 mins 136.12 g 141.03 g After 5 mins 142.25 g 137.97 g After 10 mins 142.

82 g 138.28 g After 15 mins 142.61 g 137.84 g After 20 mins 143.36 g 138.38 g After 25 mins 143.

49 g 138.17 g       In the experiment, pig intestines wereused as dialyzing membrane to imitate the function of the plasma membrane. TheNaCl filled dialyzing membrane absorbed water from the water solution at thestart of the experiment while the water filled dialyzing membrane lost itswater to the NaCl solution. However, as the osmosis continues for 30 minutes,the rate of the two set-ups decreased as the solution outside and inside thedialyzing membranes slowly reaches equilibrium. A notable inconstant decrease ofthe weight was observed in the water filled membrane which may be caused by theattempt of the membrane to reach equilibrium.III.          Hemolysis and CrenationThe net movementof water in and out of the cell is driven by the difference in osmotic pressurebetween the extracellular and intracellular fluids (Finkler, n.d.

). Thus, theextracellular fluid has an important role to the cell. The effect of theextracellular fluid to the cell is called tonicity (Finkler, n.d.). It can beisotonic which means that the osmotic concentration of the extracellular fluidis the same with that of the fluid inside the cell.

Hypotonic, which means thatthe osmotic concentration of the extracellular fluid is lower than that of thecell and hypertonic if the extracellular fluid is higher than that of the cell.      Figure3. Illustration of red blood cells when exposed to (A) distilled water, (B)0.

9% NaCl and (C) 3% NaCl.Under themicroscope, the red blood cells from the solution with distilled water swelledand burst (Figure 3.A). This is because the osmotic concentration outside thecell is lower than that of the inside of the cell, the water tends to moveinside the cell.  In the solution with0.

9% NaCl, there was no apparent change to the red blood cells (Figure 3. B)because the osmotic concentrations inside and outside the cell are equal so thenet movement of water is zero. Lastly, the red blood cells of the solutioncontaining 3.0% NaCl shriveled (Figure 3.C). This is because the osmoticconcentration of the extracellular fluid is higher than that of the cell’sfluid, the water tends to go outside the cell. IV.

         DialysisA dialyzingmembrane is used to mimic the function of the kidney to filter the blood andtransport it to the different organs of the body. These membranes allow onlyspecific molecules to pass through such as low molecular weight molecules whileblocking other large molecules such as proteins and albumin (To et al, 2015). In theexperiment, the researchers obtained a piece of dialyzing membrane. This wasthen filled with a solution composed of 1%boiled starch, a pinch of sodiumchloride, 20mL glucose and small albumin. The dialyzing membrane was immersedin a beaker filled with distilled water. After 30 minutes, the water outsidethe dialyzing membrane was tested for the following:A.     Test for sodium chloride    Figure4. Solution after the addition of silver nitrate.

The solution iscolorless. The absence of any precipitate indicates a negative result for the testfor sodium chloride. Supposedly, the small molecules and ions (Na+,Cl-) should have pass out the surrounding solution which would givea positive result for the sodium chloride test (Shreya, n.d.). The negativeresult could have been caused by the remaining fats surrounding the intestinewhich could have blocked the passage.B.     Test for starch    Figure5.

Solution after the addition of IKI.The solution iscolored reddish brown, which is the color of the IKI. The absence of anyblue-black color in the solution indicates a negative result for the test forstarch. This is because the starch molecules are too large to pass through themembrane thus remaining inside the intestine (Selective Permeability &Dialysis, n.d.).C.     Testfor glucose    Figure6.

Solution after the addition of Benedict’s solution.The solution is lightblue, which is the color of Benedict’s solution. The absence of any precipitateeven after the boiling of the solution in a water bath indicates a negativeresult for the test for glucose. Supposedly, glucose has small molecules thatcan pass through the membrane which would then give a positive test result(Selective Permeability & Dialysis, n.d.

). The negative result could havebeen due to the remaining fats surrounding the intestine which could preventthe passage of molecules.D.     Testfor albumin    Figure 7. Solution after theaddition of concentrated nitric acid.The solution wascolorless which also lacked any precipitate, indicating a negative test resultfor albumin. Albumin is made up of proteins that has molecules that are too bigto pass through the membrane. Thus, they are only present inside the membrane(Selective Permeability & Dialysis, n.

d.).CONCLUSIONThereare different types of cell membrane transport which allows specific moleculesto pass through. This kind of transport system works for the cells and the bodybecause the restrictions of some molecules makes the function of the plasma membraneand the cells to be more efficient.LITERATURE CITEDFinkler, M.(n.d.) Osmosis, Tonicity, and Concentration.

IndianaUniversity KokomoScience, Mathematics, and Informatics Department T., (1829). A Short Account of Experimental Researches onthe Diffusion of Gases Through Each Other, and their Separation by MechanicalMeans.

Quart. J. Sci., 2, pp.

 74-83Hsu, J. and Liu, B. (1993). Dissolutionof solid particles in liquids: A reaction—diffusion model. Colloids andSurfaces, 69(4), pp.

229-238.Linge (1981),Adv. Colloid. Interface Sci.. 14. pp 239. Selective Permeability &Dialysis.

n.d.  http://bio662.dyndnsinfo/S3B/B3N/b3n01FoodNutrition/b3n01eFdN441SelectivePermeability.

htmShreya, C.,n.d. Experiment on Dialysis (With Diagram) | Physics. online BiologyDiscussion. ofDiffusion of Solids in Liquids | Chemistry Science Fair Project. (2015). http://www.seminarsonly.

com/Engineering-Projects/Chemistry/Study-of-Diffusion-of-solids-in-liquids.php To, N., Sanada, I., Ito, H., Prihandana, G., Morita,S., Kanno, Y.

and Miki, N. (2015). Water-Permeable Dialysis Membranes forMulti-Layered Microdialysis System. Frontiers in Bioengineering andBiotechnology, 3.Wisniak, J. (2013). Thomas Graham.

II. Contributions todiffusion of gases and liquids, colloids, dialysis, and osmosis. EducaciónQuímica, 24, pp.506-515.

Why doesdiffusion take place. (2016). A plus topper.  


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