1. How Does Stuff Get Into and Out of the Cell
Cell Movement
How Does Stuff Get Into and Out of the Cell

2. Major Factor Cell Membranes
All cells have a cell membrane
Functions:
Controls what enters and exits the cell to maintain an internal balance called homeostasis
Provides protection and support for the cell

3. About Cell Membranes Cell membranes have pores (holes) in it
Selectively permeable: Allows some molecules in and keeps other molecules out
The structure helps it be selective!
Pores

4. Define selectively permeable membrane
A membrane that allows only certain materials to cross it
Materials pass through pores in the membrane
Small molecules pass through – ex: water
Large molecules can’t pass through – ex: proteins and complex carbohydrates

5. KEY CONCEPT… Materials move across membranes because of concentration differences.
HIGH to LOW
NO ENERGY
Energy NOT REQUIRED for particles to move from areas of HIGH concentration to areas of LOW concentration. (Passive Transport)
Energy REQUIRED for particles to move from areas of LOW concentration to HIGH concentration. (Active Transport)
LOW to HIGH
ENERGY

6. Types of Cellular Transport
high
low
Weeee!!!
Passive Transport
- cell does not use energy
Diffusion (of small particles)
Osmosis
Active Transport
- cell does use energy
Endocytosis
Exocytosis
high
low
This is gonna be hard work!!

7. Passive Transport
cell uses no energy
molecules move randomly
Molecules spread out from an area of high concentration to an area of low concentration.
(High  Low)

8. Passive Transport: 1. Diffusion
Diffusion: random movement of particles from an area of high concentration to an area of low concentration.
(High to Low)
Diffusion continues until all molecules are evenly spaced (equilibrium is reached)-
Note: molecules will still move around but stay spread out.

9. Diffusion
The movement of molecules from a area in which they are highly concentrated to a area in which they are less concentrated.
Occurs without control or energy use
Affected by:
Size of molecules
Size of pores in a membrane
Temperature

10. Passive Transport: 2. Osmosis
Osmosis animation
2. Osmosis:
diffusion of water through a selectively permeable membrane.
Water moves from high to low concentrations
Water moves freely through pores.

11. (Low  High) Active Transport cell uses energy
actively moves molecules to where they are needed
Movement from an area of low concentration to an area of high concentration
(Low  High)

12. Endocytosis
Very large molecules or substances must enter the cell by the membrane pinching inward:

13. Types of Active Transport Endocytosis
1. Endocytosis: taking bulky material into a cell
Uses energy
Cell membrane in-folds around food particle
“cell eating”
forms food vacuole & digests food
This is how white blood cells eat bacteria!

14. Endocytosis in action…..

15. Exocytosis
The cell gets rid of secretions or wastes

16. Types of Active Transport
Exocytosis: Forces material out of cell in bulk
membrane surrounding the material fuses with cell membrane
Cell changes shape – requires energy
EX: Hormones or wastes released from cell

17. Why are osmosis & diffusion important?

18. Why are osmosis & diffusion important?
All living things have certain requirements they must satisfy in order to remain alive – maintain homeostasis
These include exchanging gases (usually CO2 and O2), taking in water, minerals, and food, and eliminating wastes.
These tasks happen at the cellular level.
Molecules move through the cell membrane by diffusion.