Membrane Permeability

The Neurophysiology of eye Impulses and Effects of Inhibitory Chemicals on their Action Potentials Aferdita Sabani Biol 2401. C5L Dr. Endley March 20, 2013 Introduction Cell structure and function female genitalia be defined in many aspects but one the most important characteristic is that it is envelop inwardly a cell membrane called a plasma membrane. The plasma membrane is by-layer composed of lipids and insert proteins. This membrane is semi-permeable due to its hydrophobic and hydrophilic regions.At the boundary of every cell the plasma membrane functions as a selective barrier that allows nutrients to be brought in and/or re actuated from inside the cell. The cells permeability and bring mechanisms allow for this occurrence and it is vital for a functional and healthy cell. Transport through with(predicate) the plasma membrane occurs in two basic counselings motionless and active processes. The passive transport process is set by the concentration or pressure differe nces betwixt the interior and exterior environment of the cell.According to Kenyan college biological science department, Simple scattering is when a beautiful non-polar molecule passes through a lipid bilayer. It is classified as a means of passive transport. In simple diffusion, a hydrophobic molecule can journey into the hydrophobic region of the membrane with knocked out(p) getting rejected. Particles diffuse passively through small pores within the plasma membrane and they also move from an environment of high concentration towards an environment with lower concentration. Osmosis is a type of diffusion when it comes to water transport.Both diffusion and osmoses move substances smooth their concentration gradient. Facilitated diffusion is also passive transport, but does non involve the simple movement through pores and lipid dissolving. In this case a newsboy protein in the membrane is introduced to facilitate the transport of substances down their concentration gradien t. Active transport is not passive because energy in the form of cellular adenosine triphosphate is required to drive the substances across the membrane, in that respectfor the cell must spend some f its energy to get through or move against the concentration gradient. In one type of active transport the substance gets across the membrane by forming a substrate enzyme complex where the substance is picked up by a carrier protein and are thus able to move into cell. This combination is lipid and pear-shaped so energy is needed to defy debate forces. According to Pearson/biology, Active transport uses energy to move a solute uphill against its gradient, whereas in facilitated diffusion, a solute moves down its concentration gradient and no energy input is required. If an try was conducted where the conditions of transportation were manipulated by adding in larger membrane pores, increasing protein carriers, increasing pressure and adding higher levels of adenosine triphosphate for active transport the rates of alter allow for improver providing an optimal level of reactions. Experimental Methods and Materials In conducting this experiment the materials needed were a calculator the PhysioEX 8. 0 C D and the Anatomy and Physiology Lab Manual because this was a computer simulated experiment. use One Simple airingTwo beakers were placed following to each other and joined by a membrane holder. Four membranes were used and each possessed a different molecular weight cut withdraw (MWCO) consisting of 20, 50, deoxycytidine monophosphate, and 200 MWCO and were tested using NaCl, Urea, Albumin, and Glucose solutions. First, the 20 MWCO membrane was placed in the membrane holder between the beakers and the first solute studied was NaCl. A 9mM concentrated solution was dispersed into the left field beaker and the set beaker was filled with deionized water. This shift was allowed 60 minutes.At the end of this time lapse the results were recorded (see result section of the report). The 20 MWCO membrane was distant and each beaker was flushed for the near run. A membrane with the 50 MWCO was placed between the beakers and the steps performed supra were recurrent using the 9 mM NaCl solution for 60 min. and then repeated again for the ascorbic acid and 200 MWCO, as described by the A & P Lab Manual by Marieb and Mitchell. The next solutions tested were Albumin, Urea, and Glucose. All were placed into the left beaker independently and the tests were run exactly like that for NaCl. legal action Two Facilitated Diffusion In this experiment the set-up of the two beakers and membrane holder was used again. Only NaCl and Glucose solutes were used and membranes with viosterol, 700 and 900 glucose carrier proteins The 500 membrane was placed between the beakers and the glucose solution with a concentration of 2. 00mM was delivered to the left beaker. The right beaker was filled with deionized water. The timepiece was set for 60 minutes. Wh en the time was up the data was recorded and the beakers were flushed to set up for the next run.The same steps were repeated using the 2. 00 mM glucose solution with the 700 and 900 carrier protein membranes, separately for 60 minutes. The survive run of this transport mechanism was done by increasing the 2. 00mM to 8. 00mM glucose concentration. This experiment was done the same way as above for each of the 500, 700 and 900 carrier protein membranes for 60 min. respectively. Activity 3 osmotic Pressure In this experiment pressure readers were added in order measure osmotic pressure change and were placed on top the two beakers.A 20 MWCO membrane was placed between the beakers and a NaCl concentration of 8mM was put into the left beaker. Deionized water was placed into the right beaker. Time was set at 60 minutes. The pressure steps were repeated with the 50, 100 and 200 MWCO membranes Activity 4 Active Transport This experiment resembled the osmosis experiment except that an ATP dispenser was substituted for the pressure meters on top of the beakers. In this experiment it was assumed that the left beaker was the inside of the cell and the right beaker was the extracellular space.The membrane used had 500 glucose carrier proteins and 500 sodium-potassium pumps. Membrane was placed between the beakers and a NaCl concentration of 9. 00mM was delivered into the left beaker and a KCl concentration of 6mM was deal out into the right beaker. The ATP was the changing variable in this experiment. 1mM of ATP was dispensed and withdraw was observed for 60 min. It was observed when no ATPmM was applied and finally when 3mM ATP was applied. Results Activity 1 Simple Diffusion TABLE 1 Dialysis Results (average diffusion rate in mM/min) Solute Membrane (MWCO) 20 50 100 200 NaCl No diffusion 0. 0150 0. 0150 0. 0150 Urea No diffusion No diffusion 0. 0094 0. 0094 Albumin No diffusion No diffusion No diffusion No diffusion Glucose No diffusion No diffusion No diffusion 0. 0040 NaCl had no diffusion until the 50 MWCO was introduced and then it had a unvaried rate through the larger pored membranes. Urea diffused at 100 MWCO and up. Albumin had no diffusion through any of the membranes and Glucose diffused only through the 200 MWCO membrane. Activity 2 Facilitated Diffusion TABLE 2Facilitated Diffusion Results (glucose transport rate (mM/min) Number of glucose carrier proteins Glucose concentration(m/M) 500 700 900 2. 00 0. 0008 0. 0010 0. 0012 8. 00 0. 0023 0. 0031 0. 0038 As the tour of glucose carrier proteins improverd so did the rate of transfer for both concentrations of glucose. The higher concentration of the 8. 00 m/M had a faster rate than that of the 2. 00 m/M glucose concentration Activity 3 Osmotic Pressure TABLE 3 Membrane (MWCO) Solute 20 50 100 200 Na* Cl- 272 0 0 0 Albumin 136 136 136 136Glucose 136 136 136 0 The osmotic pressure was highest and only occurred with the 20 MWCO membrane. Albumin had a constant pressure of 136 mm Hg with every membrane and Glucose had constant pressure of 136 mm Hg until it was relieved when the 200 MWCO membrane was introduced. Activity 4 Active Transport Table 4 acquit 1 Solute ATP buy the farm Conc. L Start Conc. R Pumps Carriers Rate Na* 1. 00 9. 00 0. 00 500 0. 0270 K* 1. 00 0. 00 6. 00 500 0. 0180 Glucose 0. 00 0. 00 - 500 0. 0000 Run 2 Solute ATP Start Conc. L Start Conc.R Pumps Carriers Rate Na* 0. 00 9. 00 0. 00 500 0. 0000 K* 0. 00 0. 00 6. 00 500 - 0. 0000 Glucose - 0. 00 0. 00 500 0. 0000 Run 3 Solute ATP Start Conc. L Start Conc. R Pumps Carriers Rate Na* 3. 00 9. 00 0. 00 500 0. 0050 K* 3. 00 0. 00 6. 00 500 0. 0033 Glucose 0. 00 0. 00 500 0. 0000 When 1 ATP was dispensed the Na and K transported at a higher rate than when 3 ATP was dispensed and in that location was no transport when ATP was absent. Discussion Activity 1 Simple DiffusionUpon observing the results for all of the solutes with the 20 MWCO membrane between the left beaker and the artifi cial external environment of deionized water in the right beaker no diffusion occurred, because the pores were not large enough for them to pass through. An observation that is important to note is that even the small ions of NaCl did not diffused here, so it is obvious that the other molecules would also not diffuse. At 50 MWCO the pores were full large enough for the dissociated NaCl ions to get through but the threshold stopped there because Urea, Albumin and Glucose molecules in the solute were too large.Observations of the diffusion of the solutes with the 100 MWCO membrane showed that all but albumin and Glucose passed, so urea coat was now compatible for the size of this pore. Finally, when the 200 MWCO membrane was introduced everything except Glucose got through because it is a very large molecule that cannot diffuse simply. It must be facilitated. Activity 2 Facilitated Diffusion In the facilitated diffusion of Glucose the parameters that were introduced were the number of carrier proteins available for transport in the membrane.According to the results, when there was a 2. 00mM concentration of Glucose in the left beaker there was evidence of diffusion based on the measured rate of diffusion in mM/min. As the number of carrier proteins increased by 200 between 500 and 900 the rate between 0 . 0008 to 0. 0012mM/ min also increased by 0. 0002 min into the beaker. When 8. 00mM of Glucose was placed in the left beaker with the same carrier protein membrane criteria of 500, 700, and 800 the rate increased. The rate was actually faster than that of the 2. 00 mM concentration.As the concentration of glucose raised the demand for the protein adherence increased so more carrier proteins got involved, while previously some were just hanging out because there was less glucose to transfer. Activity 3 Osmosis In this experiment the study was based on the transfer of water across a membrane. Osmosis of water tends to balance out concentrations, so it will flow to an knowledge base of higher solute concentration. Water flowing to a more concentrated solution will usually increase in volume but in this closed system for the experiment the focus was on the increase of pressure.The solutes were confined to their area by a semi-permeable membrane based on the pores of the membrane and the size of the molecules in the solute. With 8mM of NaCl with a 20 MWCO membrane the pressure reading was 272 mHg because the salt was not able to pass through the membrane, but the water diffused to the salt side so there was pressure causing and odds-on balance, but with the membranes of 50, 100 and 200 MWCO there was no pressure because the membrane became permeable to the salt allowing an balance between he beakers, therefore no pressure. In the case of Albumin, the water diffused building up pressure until there was no more water left to diffuse so pressure remained constant at all MWCOs. The same occurred with Glucose until the membrane was replaced wit h the 200 MWCO membrane. Glucose was able to diffuse thus resulting in counterweight in both beakers. Pressure will rise until equilibrium is obtained. Activity 4 Active TransportThe experiment showed that at 1 ATP the reaction took place at very slow rate and not completely. Without ATP the transfer didnt take place at all. When 3 ATPs were added transfer took place quickly and almost completely. The more ATP introduced to the cell, the faster and more complete the transport will occur which is very important for the transport of glucose since it is a substrate for the production of more ATP.