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Cell Transport Mechanisms and Permeability Essay Sample

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Cell Transport Mechanisms and Permeability Essay Sample

1.Describe two variables that affect the rate of diffusion. Size of material and concentration 2.Why do you think the urea was not able to diffuse through the 20 MWCO membrane? How well did the results compare with your prediction? The molecules were too large to pass through. This is what I predicted on my Hypothesis. 3.Describe the results of the attempts to diffuse glucose and albumin through the 200 MWCO membrane. How well did the results compare with your prediction? The glucose diffused through the 200 MCWO membrane while the albumin didnt.

4.Put the following in order from smallest to largest molecular weight: glucose, sodium chloride, albumin, and urea. Sodium chloride urea glucose albumin

Activity 2 Simulated Facilitated Diffusion

1.Explain one way in which facilitated diffusion is the same as simple diffusion and one way in which it differs. One way that facilitated diffusion and simple diffusion are similar is the way they transport along or down the concentration gradient. One way these two differ is that simple diffusion occurs without the assistance of membrane proteins and facilitated diffusion requires a membrane bound carrier protein to assist in transport.

2.The larger value obtained when more glucose carriers were present corresponds to an increase in the rate of glucose transport. Explain why the rate increased. How well did the results compare with your prediction? The greater the concentration difference between one side of the membrane and the other, the greater the rate of facilitated diffusion. 3.Explain your prediction for the effect Na+Cl− might have on glucose transport. In other words, explain why you picked the choice that you did. How well did the results compare with your prediction? Prediction was that NaCi would have no effect on the glucose due to saturation. Activity 3 Simulating Osmotic Pressure

1.Explain the effect that increasing the Na+Cl− concentration had on osmotic pressure and why it has this effect. How well did the results compare with your prediction? Increasing the number of non-diffusible particles increases osmotic pressure. If solutes are able to diffuse, then equilibrium will be established and osmotic pressure will not be generated. Osmotic pressure would be 0 if albumin concentration was the same on both sides of the membrane.

2.Describe one way in which osmosis is similar to simple diffusion and one way in which it is different. Osmosis is similar to diffusion involve movement of a substance an area of higher concentration to lower with or along or down the concentration gradient. One way they differ is that diffusion moves particles and ions while osmosis moves only water. 3.Solutes are sometimes measured in milliosmoles. Explain the statement, “Water chases milliosmoles.” Osmosis is the diffusion of the solvent water. The water in this simulation diffuses to the side of the membrane that has the highest concentration of solutes. 4.The conditions were 9 mM albumin in the left beaker and 10 mM glucose in the right beaker with the 200 MWCO membrane in place. Explain the results. How well did the results compare with your prediction? The pressure increased on the left. Activity 4 Simulating Filtration

1.Explain in your own words why increasing the pore size increased the filtration rate. Use an analogy to support your statement. How well did the results compare with your prediction? Increasing the pore size increases the filtration rate because more fluids and solids can pass through the membrane. 2.Which solute did not appear in the filtrate using any of the membranes? Explain why. The reason that none of the solutes were present is because the solution were too large to pass through. 3.Why did increasing the pressure increase the filtration rate but not the concentration of solutes? How well did the results compare with your prediction? It increased the filtration rate because the blood pressure increased, but the concentration of solutes did not because the pore size did not increase. ___

Activity 5 Simulating Active Transport

1.Describe the significance of using 9 mM sodium chloride inside the cell and 6 mM potassium chloride outside the cell, instead of other concentration ratios. The reason for the use of 9mM of sodium chloride is because 3 ions are ejected for every 2 K that are added. K hangs outside the cell unless actively transport inside the cell. 2.Explain why there was no sodium transport even though ATP was present. How well did the results compare with your prediction? There were no sodium ions because they were ejected by the cells by active transport.

3.Explain why the addition of glucose carriers had no effect on sodium or potassium transport. How well did the results compare with your prediction? The introduction of glucose had no effect on the sodium and potassium transport due to solute pumps. 4.Do you think glucose is being actively transported or transported by facilitated diffusion in this experiment? Explain your answer. The glucose is transported by facilitated diffusion in the experiment that is how glucose is transported. The glucose could not be actively transported because they are lipid insoluble and too large to pass through the membrane pores.

Lab Report 1

Activity 1

The purpose of this lab is to gain a better understanding of a cel’s selectively permeable membrane and the passive processes of simple diffusion.

The hypothesis of this experiment was Urea will not diffuse through the 20MWCO.

Materials and Methods
Materials
Two glass beakers
Four dialysis membranes 20MWCO, 50, 100 and 200
Four solutes: NaCi, Urea, Albumin, and Glucose
Deionized water

Date and Analysis
Table 1: Activity 1: Simulating Dialysis (Simple Diffusion) Key: Solutes that were able to diffuse into the right beaker are indicated by a “+”. Solutes that were not able to diffuse into the right beaker are indicated by a “-“.

Membrane (MWCO) Solute (9.00 mM) (Pore Size)|NaCl|Urea|Albumin|Glucose|
20|–|–|–|–|
50|+|–|–|–|
100|+|–|–|–|
200|+|–|–|+|

Results
The first solute tested was NaCi and it showed that with a 20MWCO membrane, no diffusion occurred into the right beaker. The NaCi molecules were too large to pass through the 20MWCO membrane because its pores were too small. Membranes 50 100 and 200 did allow the NaCi to pass through. As for the solute Urea, the experiment conducted showed that no diffusion occurred with all four membranes.

Activity 2
Purpose: To understand that some solutes require a carrier protein to pass through.

Hypothesis: I think increasing the number of protein carbs carries will have on the glucose transport rate

Materials and Procedure
Two glass beakers
membrane builder
glucose concentration
Solution dispenser

Membrane (MWCO) Solute|20|50|100|200|
NaCl|+|+|+|+|
Urea|+|+|+|+|
Glucose|+|+|+|+|
Powdered Charcoal|+|+|+|+|

Results

An increase in amount of glucose carrier proteins in the membranes, transport of the glucose molecules in the concentration is more effective.

Exercise 3
Purpose: To explain how osmosis is a special type of diffusion.

Hypothesis: the effect you think increasing the NaCi concentration will have?

Materials and Procedure:

Date/ Analysis: Filtration Rate and Amount of Solute Detected in Filtrate
Membrane (MWCO)
Solute|20|50|100|200|
Filtration Rate (ml/min)|
1|
2.5|
5|
10|
NaCl in filtrate (mg/ml)|
0|
4.81|
4.81|
4.81|
Urea in filtrate (mg/ml)|
0|
0|
4.74|
4.74|
Glucose in filtrate (mg/ml)|
0|
0|
0|
4.39|
Powdered Charcoal (mg/ml)|
0|
0|
0|
0|

Results
Increasing the number of non-diffusible particles increases osmotic pressure. If solutes are able to diffuse, then equilibrium will be established and osmotic pressure will not be generated.

Activity 4th

Purpose: To understand that filtration is a passive process dependent upon a pressure gradient. Hypothesis: Will the increase in pore size increase the filtration rate? Results: increasing the pore size increases the filtration rate because more fluids and solids can pass through the membrane. Materials: Two Glass beakers

Membrane Holder
4 dialysis membranes: 20, 50, 100 and 200 MWCO
4 solutions: Na+Ci-, Urea, Glucose and powdered charcoal

Table #2: Solute Residue Presence in the Membrane
Key: If solute residue was present on the membrane, it is indicated by a “+”. If solute residue was not present on the membrane, it is indicated by a “–“.

Membrane (MWCO) Solute|20|50|100|200|
NaCl|+|+|+|+|
Urea|+|+|+|+|
Glucose|+|+|+|+|
Powdered Charcoal|+|+|+|+|

Activity 5

Purpose: To understand that active transport requires cellular energy in the form of ATP. To understand coupled transport and be able to explain how the movement of sodium and potassium is independent of other solutes such as glucose.

Hypothesis: Glucose carriers will have no effect on the transport of sodium or potassium.

Results: The introduction of glucose had no effect on the sodium and potassium transport due to solute pumps.

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