1. Section 2 Moving Cellular Materials
Chapter 3
Section 2 Moving Cellular Materials

2. Passive Transport Why do we have screens on our windows at home?
A cell has a membrane that works just like your window screen
It takes in food, oxygen, & other substances
Releases wastes
It is SELECTIVELY PERMEABLE
What if the holes in your window screen were 1 inch by 1 inch???
Passive Transport

3. Passive Transport Continued..
Which way things move depend on the size of molecules or particles
The path they take through the membrane
Whether or not energy is used
THE MOVEMENT OF SUBSTANCES THROUGH THE CELL MEMBRANE WITHOUT ENERGY IS PASSIVE TRANSPORT
Passive Transport Continued..

4. Molecules moving from one area where there are more of them to an area where there are fewer of them
Ex: perfume
This is still a type of passive transport
The molecules will continue to move from one area to another until they are equal in both areas
Diffusion

5. When the molecules are balanced out, we call this equilibrium
After equilibrium is reached it is maintained because molecule continue to move
Equilibrium

6. Osmosis- The Diffusion of Water
The diffusion of water through the cell membrane is referred to as osmosis
Osmosis- The Diffusion of Water

7. Osmosis

8. Where does osmosis occur?
In plant cells- for example the carrot experiment
-losing water from a plant cell causes its cell membrane to come away from its cell wall. This reduces pressure against the cell wall and a plant cell become limp- like the carrot
In animal cells- if too much water enters the cell it will burst!
Where does osmosis occur?

9. Swollen- Normal- Shriveled

10. Facilitated Diffusion
Molecules are SO large they can only enter the cell with the help of molecules in the cell membrane called transport proteins
Think of it like a fast-food restaurant- if you hand money in the drive through window they hand back your change and food. Without giving them money- you wouldn’t get food
Facilitated Diffusion

11. Without the protein opening up to let the molecule in- there is not a way in because it is too large.

12. When a substance is needed inside a cell even though the amount of that substance inside the cell is already greater than the amount outside the cell
For ex- You leave the football game and get outside of the gates when you realize your forgot your jacket in the bleachers. You have to squeeze back through the crowd at the gates to get your jacket. You will have to push and squeeze (use energy) to get back through everyone.
Active Transport

13. Getting through the crowd takes effort

14. Active Transport uses energy!

16. The process of taking a substance into a cell by surrounding it with the cell membrane
Usually these molecules and particles are too large to move by diffusion or to use the cell membrane transport proteins.
The cell membrane actually folds in on itself, enclosing the item in a sphere called a vesicle
Endocytosis

18. When the contents of a vesicle are RELEASED by a cell (moved out)
A vesicles membrane fuses with the cell’s membrane and the vesicles contents are released
Exocytosis