Laboratory #1 - Cell Physiology
1. Describe two variables that affect the rate of diffusion.
Two variables that affect the rate of diffusion are the MWCO membrane and the solute concentration. Increasing the membrane size and solute concentration will also increase the average diffusion rate. Decreasing the membrane size and solute concentration will reduce diffusion rates and can even prevent all diffusion.
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 urea was not able to diffuse through the 20 MWCO membrane because the molecular weight was too high. For a molecular weight of 60.07, a larger membrane would need to be …show more content…
The results were the same as my prediction. Increasing Na+Cl- caused an increase in pressure.
2. Describe one way in which osmosis is similar to simple diffusion and one way in which it is different.
One way in which osmosis is similar to simple diffusion is that both diffusions occur down the concentration gradient? One way in which osmosis is different than simple diffusion is that increasing solute concentrations will lead to higher osmotic pressure.
3. Solutes are sometimes measured in milliosmoles. Explain the statement, “Water chases milliosmoles.”
The statement "Water chases milliosmoles" means that water will diffuse to areas with a higher solute concentration. Increasing a solute will result in a decrease in water on one side.
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 run involving 9mM albumin in the left beaker and 10mM glucose in the right beaker resulted in a pressure increase above the left beaker. Albumin did not diffuse through the 200 MWCO membrane, while glucose diffused slightly. Albumin has a very high molecular weight so the pressure built up in the left beaker. The results were the same as my prediction that assumed pressure would be above the left beaker.
Review Sheet 4 Results