Lab 1: Simple Diffusion
Activity 1: Simulating Simple diffusion
1.What is the molecular weight of Na+? 22.99
2.What is the molecular weight of Cl-? 35.45
3.Which MWCO dialysis membranes allowed both of these ions through? 50/100/200 4.Which materials diffused from the left beaker to the right beaker? 50/100/200 5.Which did not? Why? 20 MWCO
Activity 2: Simulating Dialysis
1.What happens to the urea concentration in the left beaker (the patient)? The urea equally distributed between the two beakers. 2.Why does this occur?
The urea has diffused from the left beaker to the right beaker. The urea moved from an area of higher concentration (the left beaker) to an area of lower concentration (the right beaker, which originally contained no urea).
Activity 3: Facilitated Diffusion
1.At a given glucose concentration, how does the amount of time it takes to reach equilibrium change with the number of carriers used to “build” the membranes? As the glucose carrier proteins increase the amount of time it takes to reach equilibrium decreases. 2.Does the diffusion rate of Na+/Cl- change with the number of receptors? No 3.What is the mechanism of the Na+/Cl- transport?
It’s simple diffusion because the glucose that’s actively transported not the salt. If it did the amount of NaCl transported would increase with the number of receptors. The receptors are specific for glucose.
4.If you put the same amount of glucose in the right beaker as in the left, would you be able to observe any diffusion? No
5.Does being unable to observe diffusion necessarily mean that diffusion is not taking place? No
Activity 4: Osmosis
1.Did you observe any pressure changes during the experiment? If so, in which beaker(s), and with which membranes? Pressure changes occurred in the 20 MWCO 2.Why? This is due to osmotic pressure
3.Did the Na+/Cl- diffuse from the left beaker to the right beaker? If so, with which membrane(s)? No 4.Why?
5.Explain the relationship between solute concentration and osmotic pressure? Osmotic Pressure is the amount of pressure that needs to be supplied to the 2nd beaker in order to prevent water entry from the 1st beaker. Solute concentration depends on osmosis. 6.Does diffusion allow osmotic pressure to be generated? No
7.Would pressure be generated if solute concentrations were equal on both sides of the membrane? No 8.Why or why not? They are isotonic, they do not contribute to the tonicity of a solution as they pass through 9.Would pressure be generated if you had 9 mM glucose on one side of a 200 MWCO membrane and 9 mM NaCl on the other side? If so, which solution was generating the pressure? No 10.Would pressure be generated if you had 9 mM albumin on one side of a 200 MWCO membrane and 9 mM NaCl on the other side? If so, which solution was generating the pressure? Yes, the albumin
Activity 5: Filtration
1.What were the results of your initial membrane analysis? The concentration in filtrate was 0 for all and the membrane residue analysis showed all were present. 2.Does the membrane MWCO affect filtration rate? Yes
3.Does the amount of pressure applied affect the filtration rate? No 4.Did all solutes pass through all the membranes? Yes and no. There were traces of the powdered charcoal on the residue analysis, but the charcoal did not show up on the concentration. 5.If not, which one(s) did not? Charcoal
6.Why? The sizes of the pores
7.How can the body selectively increase the filtration rate of a given organ or organ system? By increasing blood vessel radius to increase fluid flow and thus pressure in the vessel going to a given organ.
Activity 6: Active Transport
1.At the end of this experimental run, did the Na+/Cl- move from the left vessel to the right vessel? No 2.Why?
Sodium transport does not occur because what ion is not available? The Na+/K+ pump requires both a sodium and ___________ presence on...
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