Lab 3 - Cells

ACTIVITY 1 Simulating Dialysis (Simple Diffusion)
1. Describe two variables that affect the rate of diffusion. __The size and the concentration.
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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 to large to go through. My results matched._
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 albumin was not able to go through and the glucose did. I predicted that neither of them will diffuse, however the glucose was able to go through._
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4. Put the following in order from smallest to largest molecular weight: glucose, sodium chloride, albumin, and urea. _sodium chloride, urea, glucose and albumin__
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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.__ Both are passive diffusion that are from high concentration gradient to a low concentration gradient. Facilitated differs from simple because it requires a carrier protein to diffuse. _
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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 rate increased because there is more room and surface area increases relative to glucose.
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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? _I picked the answer based on the activity. My results matched.
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 NaCl will increase the osmotic pressure because water needs to diffuse to the higher concentration gradient until equilibrium is reached_. My results were the same.
2. Describe one way in which osmosis is similar to simple diffusion and one way in which it is different. ___
_ Both are passive transports of high concentration gradient to low concentration gradient. Osmosis differs because it is the diffusion of water from a high to a low concentration gradient through a selective permeable membrane.__
3. Solutes are sometimes measured in milliosmoles. Explain the statement, “Water chases milliosmoles.” ___
__ Osmosis is the diffusion of the solvent, e.g. water. The water in this simulation diffuses to the side of the membrane that has the highest concentration of the 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 glucose diffuses from the right beaker to the left beaker until equilibrium is reached. The albumin cannot diffuse through the membrane. My results were off.

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? ___
_ This increase in pore size will increase the filtration rate because if it have more space, they will be able to pass through. If you connect a water hose to spray your grass, the water will come out faster than a device that attaches to water your grass. My results matched.__
2. Which solute did not appear in the filtrate using any of the membranes? Explain why. ___
_ Powdered Charcoal- It was 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? _ The pressure allows for more movement through the membrane but equilibrium was not reached.__My results were 50/50
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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 Na/K pump allows for 3:2 ratio__
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2. Explain why there was no sodium transport even though ATP was present. How well did the results compare with your prediction? __ In order for the Na+/K+ pump to function, both these ions and ATP must be in place. My results were off._
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? __ Glucose concentration does not affect the Na/K concentration. My results are off.
4. Do you think glucose is being actively transported or transported by facilitated diffusion in this experiment? Explain your answer. __ It is being transported by facilitated diffusion. Since glucose is a lipid insoluble and too large to pass through the membrane it requires a carrier but not ATP (no energy needed.)_
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