LAB EXERCISE I
After the first exercise : Simulating Simple diffusion
Which Materials diffused from the left beaker to the right beaker? NaCl , Urea , Glucose
Which did not ?
Albumin’s Composition or charge was too great to diffuse through the membrane.
After the 2nd activity : Simulating Dialysis
What happens to the urea concentration in the left beaker (the Patient)? It diffused to the right beaker
Why does this occur?
The excess amount must be diffused to reach equilibrium.
3rd exercise :Facilitated Diffusion
At ta fiven concentration, how does the amount of time it takes to reach equilibrium change with the number of carriers used to “build” the membrane? The time needed decreases
Does the Diffusion rate of Na/Cl change with the number of receptors? Yes What is the mechanism of the Na/Cl transport? The selective plasma membrane 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 they would be equal Does being unable to observe diffusion necessarily mean that diffusion is not taking place? No the rate of diffusion may be either very rapid or gradual.
4th : Osmosis
Did you observe any pressure changes during this experiment ? if so in which beakers and which membranes? I did not notice any pressure changes.
Why? Both of the pressures in the beakers were not equal.
Did the Na/Cl diffuse from the left beaker to the right beaker ? if so which memebranes? The was no diffusion in the beakers
Why ? because the pressure was not equal , diffusion could not occur Explain the relationship between solute concentration and osmotic pressure. Higher concentration higher pressure
Does diffusion allow osmotic pressure to be generated?
No, there’s no effect.
Would pressure be generated if solute concentrations were equal on both sides of the membrane? No, the pressure would be stable Why or why not? It would be stabe due to no difference in concentration Would pressure be generated if you had 9 mm glucose on one side of 200MWCo membrane and 9mm NaCl on the other side? If so which solution was generating the pressure? No it would diffuse. Would pressure be generated if you had 9mm albumin on one side of a 200 MWCO membrane 9mm NaCl on the other side? If so which solution generating the pressure? Yes, albumin generates pressure on NaCl.
5th : Filtration
What were the results of your intial membrane analysis?
All solutes are present
Does the membrane MWCO effect filtration rate?
yes it does.
Does the amount of pressure applied affect filtration rate? NO Did all the solutes pass through all the membranes? Yes
If not which one(s) did not? They were all present
Why ? The molecules were small enough to pass through membranes How can the body selectively increase the filtration rate of a give organ or organ system? By allowing larger molecules to pass through the membrane.
6th : active transport
at the end of this experimental run Na/Cl move from the left vessel to the right vessel? There was no transport why? No presence of ATP
as the run progresses, the concentration of the solutes will change in the windows next to the two beakers. The rate will slow down markedly, the stop before completed. Why? The supply of ATP will be depleted before diffusion is finished. Does the amount of NaCL /KCl transported change? Yes, it allows more diffusion. Does the amount of solute treansported across the membrane change with an increase in carreirs or pumps? No it stays the same. Is on solute more affected than the other? Na is more affected Does the membreane you built allow simple diffusion?
NO it does not.
If you placed 9mm NaCl on one side of the membrane and 15mm on the other side, would there be movement of the NaCl? No there would not be. Why? Bothe are equally concentrated.
Does the amount of ATP added make any difference? NO the results are the same.
END OF EXERCISE...