Lab lab
Nasra20
Lab5-membranesdiffusionandosmosis.pptxLab 5: Membranes, Diffusion and Osmosis
Plasma Membrane
The outer boundary of all living cells
Made of a bilayer of phospholipids studded with proteins, cholesterol and carbohydrates
Selectively permeable
Diffusion
Simple Diffusion- the passive movement of a substance down its concentration gradient (from an area of high concentration to an area of low concentration) until equilibrium across the membrane is reached
Osmosis
The diffusion of water across a semipermeable membrane
The movement of water across a membrane depends on the presence of large solutes that are trapped on one side
Water diffuses across a membrane from areas of high water concentration to low water concentration. In other words, from low solute concentration to high solute concentration to balance the concentration of solute.
Tonicity
Tonicity- the ability of a surrounding solution to cause a cell to gain or lose water by osmosis. Depends on the number of solutes that cannot cross the membrane
Hypotonic solution- has a lower concentration of solutes than inside the cell. A cell placed in this solution will gain water by osmosis and will swell and burst
Isotonic solution- has the same number of solutes as the inside of the cell, causes no NET movement of water so the volume of the cell remains the same
Hypertonic solution- has a higher concentration of solutes than inside the cell. A cell placed in this solution will lose water by osmosis and will shrivel and die
Today’s Lab
https://www.youtube.com/watch?v=jTDATlaBV-o
Instead of potatoes, we will simulate this lab with eggs. You DO NOT have to actually do this at home, but if you want to try it, you definitely can! I will give you data to analyze.
Today’s Lab
0% NaCl (pure distilled water)
4% NaCl
8% NaCl
12% NaCl
16% NaCl
20% NaCl
Things to think about:
What data should we collect?
How will we graph our data?
How will we interpret our data?
