PhysioEx Exercise 1: Activity Questions

Réussis tes devoirs et examens dès maintenant avec Quizwiz!

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?

Because the MW of the urea is 60.07, it exceeded the 20 MWCO, therefore it was unable to diffuse through the 20 MWCO membrane due to urea being unable to fit through the pores of the membrane.

Describe two variables that affect the rate of diffusion.

Concentration-As concentration increases, the rate of diffusion increases due to having a higher concentration gradient. Permeability-Membrane permeability affects the rate of diffusion. In the experiment, the membrane permeability was adjusted by varying the molecular weight cutoff (MWCO). The smaller the molecule, the faster the rate of diffusion due to ability to diffuse through the membrane pores (adjusted by the MWCO).

1. Explain one way in which facilitated diffusion is the same as simple diffusion and one way in which it is different from simple diffusion.

Facilitated diffusion is the same as simple diffusion in that facilitated diffusion requires no energy and diffuses substances down a gradient. Facilitated diffusion is different from simple diffusion in that facilitated diffusion requires carrier proteins.

Do you think glucose is being actively transported or transported by facilitated diffusion in this experiment? Explain your answer.

Glucose is being transported by facilitated diffusion because the actual process of glucose transport is done without ATP and needs only a transport protein. Glucose transport is coupled with the sodium potassium pump transport of ions to create the gradient that powers the transportation of glucose.

Explain the effect that increasing the Na+ Cl- concentration had on osmotic pressure and why it has this effect.

Increasing the NaCl concentration increased the osmotic pressure because there was an increase in force required to oppose osmosis in the closed system.

Describe one way in which osmosis is similar to simple diffusion and one way in which it is different.

Osmosis is similar to simple diffusion in that it's a passive process and moves solutes. Osmosis is different from simple diffusion because it's the movement of water rather than solutes.

Why did increasing the pressure increase the filtration rate but not the concentration of solutes? How well did the results compare with your prediction?

Pressure increased the filtration rate but not the concentration of solutes because it increased the hydrostatic pressure gradient that exists. The solute concentration gradient didn't change from Trial 3 to 4 for 200 MWCO, however the pressure gradient increase allowed for the increased rate of filtration. The steeper the pressure gradient, the faster the filtration rate.

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.

Sodium chloride won't affect the rate of glucose transport because sodium chloride is not needed for transport.

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

Sodium chloride, urea, glucose, albumin

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.

The albumin didn't pass through the membrane to diffuse due to it being too large to fit through the pores of the 200 MWCO membrane. The glucose was able to pass through a little bit because of it being a smaller molecule than albumin, therefore it had a higher diffusion rate.

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 was able to diffuse; albumin wasn't able to diffuse. The glucose has a much smaller MW than albumin, therefore it was able to diffuse through the 200 MWCO membrane.

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?

The increase in pore size increased the filtration rate because more filtrate was allowed to go through the membrane. An analogy to this is if you imagine a wall that initially had a small gate that allowed only some people through, making the rate of the transport of people slow. Then compare that to increasing the size of the small gate to a much larger gate, then the rate of the transport of people would be faster.

Which solute did not appear in the filtrate using any of the membranes? Explain why.

The powdered charcoal didn't appear in the filtrate because it has a very porous internal matrix, giving lots of surface area for adsorption to surfaces; it likely was stuck and reacted with the membrane rather than filtering through it.

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.

The rate of glucose transport increased with an increase in the presence of more glucose carriers because more molecules of glucose are able to be transported across the membrane if there are more transporters present. There is an increased sensitivity or upregulation of the transport of the glucose molecules with a higher amount of carrier proteins, therefore the rate increased as the number of glucose carriers increased.

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.

This is a 3:2 ratio, showing the ratio of sodium ions coming out of a cell and ratio of potassium going into a cell. Three potassium ions come into a cell for every two sodium ions that go out. This is the significance of simulating the sodium potassium pump ratio in a cell.

Explain why the addition of glucose carriers had no effect on sodium or potassium transport.

This is because the glucose carriers behave independently of the sodium/potassium pump. The results compared well with the prediction because the rates of the sodium/potassium pumps were the same before and after addition of the glucose carriers.

Explain why there was no sodium transport even though ATP was present.

This is because there needs to be a gradient present for the sodium potassium pump to fully be active and transport sodium. The sodium potassium pump is a cotransporting protein meaning it needs to have ATP and go up the gradient. In other words, potassium needs to be present in order for sodium to be transported.

Solutes are sometimes measured in milliosmoles. Explain the statement, "Water chases milliosmoles."

Water chases milliosomoles can be explained or translated to mean that water goes in its diffusion towards a higher concentration of solutes down a gradient.


Ensembles d'études connexes

Biology Test 2 clicker questions and important terms

View Set

Chapter 13: Organization and Control of Neural Function #1

View Set

Basics of personal nutrition HUN De Jesus Valencia College - midterm

View Set

Conducting a Job Hazard Analysis (JHA)

View Set

Nursing 1128 and 1424 Test 1 (SAC Nursing)

View Set