Cd Stimulation Cellular Transport: Cell Transport Mechanisms and Permeability
Activity 1: Stimulating Dialysis (Simple Diffusion)
1. Describe two variables that affect the rate of diffusion.
The two variables that affect the rate of diffusion are:
• The composition of the lipid layer, this content varies from tissue to tissue. For example kidney tissues have a high cholesterol content which makes them impermeable to water.
• The size of the molecule, the larger the molecule the slower the rate of diffusion.
2. Why do you think the urea was not able to diffuse through 20 MWCO? How well did the results compare with your predictions?
The urea was not able to diffuse through the 20 MWCO because the membrane pores are too small and the urea molecules are large. The molecular weight of Urea is 60.07 g/mol which is too large thus the molecules were not able to pass through the pores of the 20 MWCO.
The results that I obtained from the experiment agreed with these predictions because urea was no able to diffuse through the 20 MWCO.
3. Describe the results of the attempts to diffuse glucose and albumin through the 200 MWCO membranes. How well did the results compare with your predictions?
Glucose was able to diffuse through the 200 MWCO membrane, however albumin was not able to diffuse through the 200 MWCO. This is due to the difference of the molecular weight between the two molecules. Glucose has a molecular weight of about 180 g/mol and albumin (a protein composed of 67 amino acids and each amino acid is 67 g/mol) has a molecular weight of (67 *135 g/mol) 9045 g/mol. By comparing these numerical values we can understand why albumin was not able to diffuse through the 200 MWCO.
The results that I obtained from the experiment supported these predictions because only glucose was able to diffuse through the 200 MWCO.
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: Stimulated Facilitated
1. Describe two variables that affect the rate of diffusion.
The two variables that affect the rate of diffusion are:
• The composition of the lipid layer, this content varies from tissue to tissue. For example kidney tissues have a high cholesterol content which makes them impermeable to water.
• The size of the molecule, the larger the molecule the slower the rate of diffusion.
2. Why do you think the urea was not able to diffuse through 20 MWCO? How well did the results compare with your predictions?
The urea was not able to diffuse through the 20 MWCO because the membrane pores are too small and the urea molecules are large. The molecular weight of Urea is 60.07 g/mol which is too large thus the molecules were not able to pass through the pores of the 20 MWCO.
The results that I obtained from the experiment agreed with these predictions because urea was no able to diffuse through the 20 MWCO.
3. Describe the results of the attempts to diffuse glucose and albumin through the 200 MWCO membranes. How well did the results compare with your predictions?
Glucose was able to diffuse through the 200 MWCO membrane, however albumin was not able to diffuse through the 200 MWCO. This is due to the difference of the molecular weight between the two molecules. Glucose has a molecular weight of about 180 g/mol and albumin (a protein composed of 67 amino acids and each amino acid is 67 g/mol) has a molecular weight of (67 *135 g/mol) 9045 g/mol. By comparing these numerical values we can understand why albumin was not able to diffuse through the 200 MWCO.
The results that I obtained from the experiment supported these predictions because only glucose was able to diffuse through the 200 MWCO.
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: Stimulated Facilitated