osmosis diffusion

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Post on 05-Jul-2015




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from students in the UR tech integration class


  • 1. Cells
    Diffusion and Osmosis

2. Cells have to control what leaves and what enters the cytoplasm.
3. Concentration Gradient
Water and solutes move according to their concentration gradient
Everything naturally moves away from where it is concentrated and towards where it is less concentrated
This natural movement is called diffusion.
4. Concentration gradients
Concentration gradients form when there is a difference in concentration between two places
Diffusion takes place until the concentration reaches equilibrium
5. Diffusion naturally tries to equalize concentration of water and solutes
6. Carbon dioxide naturally diffuses out of animal cells because animal cells produce CO2 as they make energy from food.The concentration inside is higher, so the net movement of CO2 is outward.
7. Movement of CO2 and O2
Oxygen naturally diffuses into animal cells because they use up oxygen as they turn food into energy
Carbon dioxide builds up as cells use the oxygen
The concentration of oxygen outside is higher, so the net movement of O2 is inward.
The concentration of CO2 is higher inside the cell and has a net movement outside the cell.
8. The cell membrane does not stop the diffusion of CO2, O2, or water molecules
9. CO2, O2, and H2O are small molecules
they each move down their individual concentration gradients until equilibrium is reached.
10. Salts and sugars cannot get through the bilayer, but water can
This makes the cell membrane semipermeable.
The movement of water through a semipermeable membrane that blocks solutes from moving is called osmosis.
11. Osmosis is the diffusion of water through a semipermeable membrane
12. Osmosis
Osmosis is used by plants to lift water upward. All the plants cells must do is maintain a higher solute concentration inside their cells.
13. Osmosis can pull water into of a cell if the cell is placed in an environment with a lower solute concentration
14. Hypotonic Solutions
Hypotonic means lower solute concentration
animal cells can rupture in hypotonic environments
plant cells are protected from rupture by their strong cell walls
15. Osmosis can also pull water out of a cell if the cell is placed in an environment with a higher solute concentration
16. Hypertonic Solutions
Hypertonic means higher concentration of solutes
A cell placed in a hypertonic environment will lose water and shrink.
Plant cells plasmolyze when placed in very salty water.
17. Isotonic Solutions
Isotonic means balanced
Cells in an isotonic environment experience no net flow of water due to osmosis.
The water flowing in is balanced by the water flowing out
18. Red Blood Cells in a Range of Solutions
19. 20. Summary
Hypertonic = higher = dehydrating environment, cells shrink
Hypotonic = lower = bloating environment, cells swell
Isotonic = equal =homeostatic environment, cells happy
21. Hypertonic, Hypotonic, and Isotonic Examples
Solution Examples
Quick Osmosis Movie
22. Experiment Videos
Iodine Ziplock Experiment
Lettuce Experiment
Egg Experiment