Osmosis, diffusion and cellular transport Flashcards
What is Diffusion?
Movement of solute from regions of greater concentration to lower concentration - to equalize the distribution of solute in the solution (may pass through a membrane)
What is Osmosis?
Movement of water through a selective membrane from low solute concentration to high solute concentration - while diffusion of solute is restricted by the membrane
Formula Osmolarity:
Molarity: moles / L (solvent
Osmolarity: moles / L * # particles
What happens to osmolarity if you have more than one type of molecule in solution?
Osmolarity is additive
What happened with the sugar molecules in the experiment?
The water went from the side of lower concentration of solute to higher concentration of solute - Osmosis
What happened with the NaHCO3(-) molecules in the experiment?
What was the proof of the movement?
NaHCO3 dissociated into Na+ and HCO3-, the particles were small enough to pass the membrane -> flow from high concentration to low concentration of solute - Diffusion
Proof: pH indicator because HCO3(-) is base
What happened with Albumin in the experiment?
Albumin is too large to pass the membrane - so no Diffusion
Water went from a low concentration of solute to a high concentration of solute
What happened when Trypsin was added to Albumin in the experiment?
Trypsin broke down Albumin, so Diffusion to the other side was possible -> detected by reagent
Also caused osmosis because of an increase in # particles: water from low concentration to high concentration of albumin
-> Equilibrity of volume
What are Caco-2 cells?
They are similar to human intestinal epithelial cells with apical and basolateral side + transporter, efflux pumps and tight junctions preventing movement between cells (paracellular transport)
What does transcellular transport depend on?
On the transporter and pumps located on the surface of the cell
What are Caco-2 cells used for?
In the pharmaceutical industry to test permeability and bioavailability of orally administered drugs
What is the function of efflux pumps?
They pump drugs out of the cell ->
MDR: multiple drug resistance proteins (p-glycoprotein)
Where is p-glycoprotein located?
Apical side of the cell
What can be predicted by permeability across Caco-2 monolayers?
-Human permeability of drugs
-Absorption studies
-Effect of transporters on permeability
-transporter-mediated drug-drug interaction
What assay is used to identify p-glycoprotein substrates and inhibitors and to measure drug efflux?
Bidirectional transport assay
