1. Material Flow in the Cell

2. Semipermeable Membrane
The Cell Membrane is a Semipermeable membrane – it keeps some things out and lets some things in.
Protects contents
of cell from outside
world.
Proteins are the
bouncers

3. What Materials can Pass?
What can come into the cell?
Oxygen & food & proteins
What goes out of the cell?
Waste materials
What is not allowed in?
Poison and waste

4. PASSIVE TRANSPORT
PASSIVE TRANSPORT – ways to move material into and out of the cell without using any energy.
2 Ways:
DIFFUSION
OSMOSIS – a type of diffusion

5. DIFFUSION
The main method by which small molecules move across the cell membrane.
The molecules move from an area of HIGHER CONCENTRATION to an area of LOWER CONCENTRATION.
Oxygen molecules commonly move into and out of the cell by Diffusion.
USES NO ENERGY (passive transport)

6. DIFFUSION DEMO
BEFORE
AFTER

7. DIFFUSION
AFTER
BEFORE

8. What Causes Diffusion?
Molecules are always moving and they bump into each other.
When they bump into each other they push each other away and spread out.
Eventually they spread throughout the whole area.
NO ENERGY NEEDED by cell because the molecules have energy in their vibrations.

9. OSMOSIS A special kind of diffusion
The diffusion of water molecules through the cell membrane.
Water still moves from HIGHER CONCENTRATION to LOWER CONCENTRATION.
USES NO ENERGY (passive transport)

10. NORMAL RED BLOOD CELL
OSMOSIS

11. RED BLOOD CELL
BEFORE

12. RED BLOOD CELL
AFTER

13. POTATO FISH!!!!
Take out a sheet of paper!
Write down observations of both of your potato slices.
Put your name on both cups
Label one cup SALT and one cup FRESH
Put the same amount of water in each cup
Put salt in the cup that is labeled salt (amount does not matter, just make sure it dissolves!)
Put one potato slice in the FRESH cup and one in the SALT cup
We are going to leave the potatoes in their cups over night.
Write down your predictions. WHAT DO YOU THINK WILL HAPPEN TO EACH OF THE POTATOES?

14. ACTIVE TRANSPORT
Active Transport – USES ENERGY to move materials into and out of the cell.
Often from LOW concentration to HIGH concentration
For small or large particles
This requires the cell to USE ENERGY.
2 ways:
ENDOCYTOSIS
EXOCYTOSIS

15. ENDOCYTOSIS USES ENERGY (active transport)
Large particles are taken INTO THE CELL
Particles include PROTEIN and FOOD

16. ENDOCYTOSIS – draw these steps
energy
energy
A WANTED
MOLECULE
STEP 1:
The cell membrane
touches the wanted
molecule. 1

17. ENDOCYTOSIS energy energy STEP 2: The cell wraps itself around
the molecule. 2

18. ENDOCYTOSIS
energy
STEP 3:
The molecule
forms a Vacuole. 3

19. ENDOCYTOSIS
energy
STEP 4:
The cell
membrane
closes. 4

20. TRANSPORT PROTEINS
These are special Proteins called Transport Proteins that are attached to the cell membrane.
They “PICK UP” the wanted molecules inside or outside of the cell and carry them in or out using energy.
Common Materials transported this way:
Calcium, Potassium, and Sodium.

21. TRANSPORT PROTEINS CYTOPLASM OUTSIDE THE CELL HIGH LOW TRANSPORT
CONCENTRATION CONCENTRATION
TRANSPORT
PROTEIN
BEFORE

22. TRANSPORT PROTEINS CYTOPLASM OUTSIDE THE CELL HIGH LOW USES ENERGY
CONCENTRATION CONCENTRATION
USES ENERGY
AFTER