1. Exchange with the environment
Chapter 2 Section 1
Exchange with the environment

2. In and Out of the Cell
Cells need to get nutrients in and wastes out
The exchange of materials between a cell and its environment occurs at the cell membrane.

3. Diffusion
Movement of particles from an area where their concentration is high to an area where the concentration is low
HIGH  LOW

4. Diffusion in cells
Diffusion can occur across cell membranes or outside of cells.
Cells do not require energy for diffusion to occur

5. Examples of Diffusion Spraying air freshener in a room
Adding a drop of food coloring to water

6. Diffusion
hill.com/sites/ /student_view0/chapter2/animati on__how_diffusion_works.html

7. The diffusion of water through a cellular membrane
Osmosis
The diffusion of water through a cellular membrane

8. Animation of osmosis
mosis.htm

9. Moving small particles
Many small particles (water and oxygen) can diffuse directly through the cell membrane due to their size
However, not all of the small particles a cell needs can do this. Sugar and amino acids aren’t small enough to diffuse through the cell membrane.
These types of particles must travel through protein “doorways” within the cell membrane.

10. Moving small particles
Passive transport
Active transport
Movement of particles in the direction of diffusion
HIGH  low
No energy required
Movement of particles against the direction of diffusion
Low  high
Requires energy (ATP)

11. Active / passive Transport
nt_resources/shared_resources/animations/ion_pump/ion pump.html

12. Moving large particles
Diffusion, passive transport and active transport are good methods of moving small particles into and out of cells.
In order to move large particles in and out cells use endocytosis and exocytosis.

13. endocytosis
During endocytosis, the cell membrane surrounds a particle and encloses it in a vesicle.
This process moves large particles into the cell.

14. exocytosis
When a large particle must be removed from the cell, it is packaged in a vesicle at the endoplasmic reticulum then travels to the cell membrane for release.