1. Osmosis Notes

2. Osmosis = Diffusion of H2O Across A Membrane
The Plasma Membrane
4/26/2017
Osmosis = Diffusion of H2O Across A Membrane
Draw this picture 
High H2O potential Low solute concentration
Low H2O potential High solute concentration
G. Podgorski, Biol. 1010

3. Osmosis Diffusion of water through a semi-permeable membrane
Semi-permeable: permeable to solvents (WATER), but not to large molecules
High [water] to low [water]
Dissolved molecules (i.e. glucose, starch) are called solutes
REMEMBER:
Water = solvent
Glucose, Starch = solutes

4. Salt Sucks Salt draws water to where it is.
Water wants to equal everything out.
A simple rule to remember is: Salt is a solute, when it is concentrated inside or outside the cell, it will draw the water in its direction. This is also why you get thirsty after eating something salty.

5. 3 Key Terms
Hypo = below
Hyper = above
Iso = equal

6. Isotonic Solution
The solution the cell is in is equal to the inside of the cell.
"ISO" means the same

7. Hypotonic The word "HYPO" means less
There are less solute (salt) molecules outside the cell then inside the cell
since salt sucks, water will move into the cell
Animal cell could burst
Plant cell wall keeps it from bursting

8. Hypertonic The word "HYPER" means more
There are more solute (salt) molecules outside the cell.
Water goes in the direction of the salt
Cell may die if too much water is lost.

9. Osmosis in Living Cells
Cellulose in cell wall
Plasmolysis = cell membrane detaching from the cell wall (shrinking)

10. Osmosis in Red Blood Cells
Isotonic
Hypotonic
Hypertonic
Iso: Normal blood cells
Hypertonic solution: the cells shrink
Cell may die if too much water is lost.
Crenation
Hypotonic solution: In animal cells, the cell may be in danger of bursting, organelles called CONTRACTILE VACUOLES will pump water out of the cell to prevent this.

11. Review Passive Transport = _____ Energy used Diffusion is defined as:
What occurs in osmosis?
Identify the 3 types of solutions.

12. Effect of Water on Cells
Hypertonic Environment
High [solute], low [water]
Cell shrinks
Hypotonic Environment
High [water], low [solute]
Cell fills with water, too much water can cause the cell to lyse
Isotonic Environment
[water] = [solute]
Normal cell: everything is equal
Hypertonic
Hypotonic
Isotonic

13. Osmosis in Plant Cells
Hypertonic
Plasmolysis
Hypertonic: In plant cells, the central vacuole loses water and the cells shrink, causing wilting.
Hypotonic
Hypotonic: In plant cells, the central vacuoles will fill and the plant becomes stiff and rigid, the cell wall keeps the plant from bursting