Cell Transport Mechanisms and Permeability Using Essay Example

style="text-align: justify;">he timer was set to 60 minutes. I pushed the start button, and watched as solute concentrations of sodium and potassium changed between the two beakers. In Run 2 the same procedures were done again, but this time using an ATP concentration of 3.00 mM. During Run 3, 9.00 mM of NaCl was dispensed in the left beaker and 10.00 mM of NaCl was dispensed in the right. ATP concentration was set to 1.00mM. I recorded data after each simulation run.

Simulating Facilitated Diffusion When glucose carriers in the membrane were set to 500, the glucose transport rate for 2.00 mM of glucose was .0008 mM/min. Equilibrium was reached at 43 minutes. At 700 glucose carriers the rate was .0010 mM , and equilibrium was reached at 33 minutes. When the glucose carriers was set at 900 the rate was .012 mM/min, and equilibrium was reached at 27 minutes. After changing the glucose concentration to 8.0 mM, the glucose transport rate with 500 carrier proteins was .0023 mM/min, and equilibrium was reached at 58 minutes. With the simulation set at 700 carrier proteins the rate was .0031mM/min, and equilibrium was reached at 43 minutes. When the simulation was done with 900 carrier proteins the glucose transport rate was .0038, and equilibrium was reached at 35 minutes.

Simulating Filtration With all solutes set at a concentration of 5.00 mg/ml and the MWCO set at 20, filtration stopped at 60 minutes, and the projected completion was 100 minutes. The residue analysis indicated all solutes present in the dialysis membrane. The filtrate concentrations for all solutes was 0.00 mg/ml. With all solutes set at a

concentration of 5.00 mg/m and the MWCO set at 50, the filtration completed in 40 minutes. The residue analysis indicated all solutes present in the dialysis membrane. The filtrate concentration for NaCl was 4.81 mg/ml, and 0.00 mg/ml for all remaining solutes.

With all solutes set at a concentration of 5.00 mg/ml and the MWCO set at 100, the filtration completed in 20 minutes. The residue analysis indicated all solutes present in the dialysis membrane. The filtrate concentration for NaCl was 4.81 mg/ml, urea was 4.74 mg/ml, glucose was 0.00 mg/ml, and powdered charcoal was 0.00 mg/ml. With all solutes set at a concentration of 5.00 mg/ml and the MWCO set at 200, the filtration completed in 10 minutes. The residue analysis indicated all solutes present in the dialysis membrane. The filtrate concentration for NaCl was 4.84 mg/ml, urea was 4.74 mg/ml, glucose was 4.39 mg/ml, and powdered charcoal was 0.00 mg/ml.

Simulating Active Transport In this experiment the left beaker represented the interior of the cell and the right beaker represented the exterior. With the addition of ATP, sodium was able to cross from the interior to the exterior using the sodium-potassium pumps. As ATP was increased from 1.00 mM to 3.00 mM, the rate of transport for both Na+ and K+ increased. No transport took place when 9.00 mM of NaCl was dispensed in the left beaker and 10.00mM of NaCl was dispensed in the right beaker.

Discussion

The purpose of the first experiment was to see how carrier proteins affect diffusion of the solute, glucose, across the membrane. Glucose can not cross a membrane without assistance from carrier

proteins because it is not lipid soluble and is also too large to pass through the membrane’s pores. Solute transport varied depending on the amount of carrier proteins available for the glucose. As seen in the experiment results, the rate of facilitated diffusion increased each time the number of protein carriers increased.

Equilibrium was also achieved sooner as the number of protein carriers increased. The rate of diffusion slowed down when the concentration of glucose was increased, but the number of glucose carriers stayed the same. For example at 500 glucose carriers, when the concentration of glucose was 2.00mM the rate was .0008, and when the concentration of glucose was 8.00mM the glucose transport rate was .0023. I noted that it took 43 minutes to reach equilibrium at a 2.00mM concentration, and it took 58 minutes to reach equilibrium at a 8.00 mM concentration.

The objective of Activity 4 was to observe how NaCl, urea, glucose, and powdered charcoal passed through a dialysis membrane. The membrane’s molecular weight cut off (MWCO) affected the rate of filtration. As the membrane’s MWCO increased from 20 to 200, the rate of filtration increased as well. Excluding powdered charcoal, solute concentrations in the filtrate increased as the MWCO got larger. Filtration occurs because of pressure differences between the two beakers and the pore size of the dialysis membrane. This, for example, simulates the hydrostatic pressure difference from the interior and exterior of a cell and also pore size of cell membrane. The pressure in these simulations stayed set at 50 mmHg, but the MWCO changed.

The larger the MWCO, the larger the poor size and the

solute that could pass through the membrane. During the 60 minute interval, all solutes failed to pass through the membrane when the MWCO was 20. Powdered charcoal was the only solute that could not filter through the dialysis membrane no matter the number of the molecular weight cut off. This could indicate that powdered charcoal needed a higher pressure in order to pass through the membrane or a higher MWCO. NaCl was the solute that filtered the best through the membrane at a molecular weight cut off above 20. After each run the Membrane Residue Analysis was used, and it detected solute residue in the membrane every time. This indicated that there was solute substances that could not filter through the membrane to the lower beaker, instead the solutes remained in the dialysis membrane.

In Activity 5, I experimented with the active transport of Na+ and K+. I observed that more Na+ and K+ moved better through the membrane when more ATP was dispensed. In the second run when 3.00 mM of ATP was dispensed, all of K+ filtered from the right beaker into the left. This simulated that in the body all of K+ would have crossed from the exterior of the cell into the interior using the sodium-potassium pumps. In the second run, all but .001 mM of the original 9.00mM of Na+ passed from the left beaker into the right. This indicated that the membrane is less permeable to Na+ than K+. In the final run, 9.00mM of Nacl was dispensed in the left beaker and 10.00 NaCl was dispensed in the right. This greatly affected the Na+ transport, and the

outcome was that no transport took place.