1. I can describe and explain diffusion and osmosis within cells.

2. What you need to know: What is: Describe Diffusion Describe Osmosis
Selectively Permeable Membrane
Permeable Membrane
Impermeable Membrane
Describe Diffusion
Describe Osmosis

3. What are some things that you need to do to stay alive?
Eat
Drink
breath
exercise?
How do these things get into your body? (i.e. Oxygen, water, food...)

4. Science geeky words: Allows ALL things to pass through
example: An open door
Permeable:
Selectively permeable (semi-permeable)
Impermeable
Allows SOME things to pass through
Example: A window with a screen
Allows NOTHING to pass through
Example: A wall

5. Task 1: Permeable Semi-permeable Impermeable
With your table groupings, SHOW the difference between membranes that are:
Permeable
Semi-permeable
Impermeable
Hint: Act out what happens when you meet each type of membrane
2 mins -- go!

6. The Cell Membrane: AKA Plasma Membrane
The plasma membrane bounds the cell. It controls the movement of materials into and out of the cell.
Selectively Permeable: allows some substances to enter or leave the cell while stopping others.
It's a complex double layer made up of phospholipids and proteins.

7. Demo time:
Materials:
water, food coloring
beaker, timer
Question: What will happen to the food coloring when it is added to the water?
Procedure:
Put a drop of food coloring into the water
Watch

8. So what really happened?
Why did the food coloring spread out and eventually mix evenly?
What is this called?
What will happen when a lot of time has passed?
The particles are moving around and bumping into each other, so they move around until they are evenly distributed.
Diffusion
The food coloring will be evenly spread out

9. What is Diffusion?
Right now, every cell in your body is letting water, oxygen, and food to enter and exit it.
The cell membrane functions like a “Gate Keeper” controlling what moves in and out of the cell.
Diffusion is one of the ways in which particles of water, oxygen, and food spread out evenly throughout the cell.

10. Diffusion Con’t.
Concentration: determines the direction that a substance takes through the cell membrane.
Particles move from areas of high concentration to areas of low concentration. Equal concentration allows the movement of particles in and out
equally.

11. So how does diffusion affect cells?
If oxygen is in a higher concentration outside the cell...

12. What is the most common substance found inside and around cells?
WATER!!!
Cells need water. Without it, they will die.
Why?
Water dissolves many of the substances that are used in cell processes.

13. What is Osmosis?
This is the Diffusion of WATER through a SELECTIVELY PERMEABLE MEMBRANE. It is the process to make sure that the H2O remains balance inside and outside of the cell.
H2O helps to dissolve many of the substances involved in cell process.
When H2O is lost from the cell (MOVES OUT) it leaves a high concentration of dissolved substances inside the cell.

14. Osmosis Con’t.
Draw and explain what is happening in the figures below.
Water

15. Summary questions What is a: Selectively Permeable Membrane
Impermeable Membrane
Describe Diffusion.
What is Osmosis?
How does the cell get things that it needs, like O2, H2O, ATP etc.?