1. 4A - Membranes

2. 1. Membranes –

3. 1. Membranes – Thin covering that forms the outer boundary of a cell
Made of lipids (fats) and protein
Fluid Mosaic Model – lipids form a fluid (film) in which the proteins float around in. The proteins make patterns (mosaics) in the fluid.

4. 2.Membranes are selectively permeable.
Selectively permeable means that certain molecules can go through the membranes while others can not.
Different membranes let different substances pass through them. For example some may allow sugar to pass through, while others do not.

5. 3. There are two ways that substances can pass through a membrane.
Passive Transport
Active Transport

6. 4. Passive Transport –

7. 4. Passive Transport –
Passive transport is one of the ways that substances can pass through a membrane.
The cell does NOT use its own energy with passive transport.
Two types of passive transport:
Diffusion and Osmosis

8. 5. Diffusion –

9. 5. Diffusion – One type of passive transport
Diffusion – movement of molecules from a place where there are many of them to a place where there are few of them.
Examples: Spray air freshener, Kool-Aid mix in water.

10. 6. Osmosis –

11. 6. Osmosis – One type of passive transport
Osmosis is the diffusion of water through a membrane.
Example – stentor pg.68

12. 7. Active Transport – One way substances move through a membrane.
Cells use own energy to move substances.