1. Cell Biology
Unit Three

2. Cell Membrane Characteristics & Function
Defines boundaries
Serve as location for functions
Facilitate and regulate movement of materials in & out of the cell
Detect external signals
Provides mechanisms for cell to cell communication

3. Cell Membrane Characteristics & Function

4. Cell Membrane Characteristics & Function

5. Cell Membrane Characteristics & Function
In facilitating and regulating the movement of materials in & out of the cell, the membrane is said to be selectively permeable

6. Plasma Membrane Structure
E face
Phospholipid bilayer
P face

7. Plasma Membrane Structure Membrane Protein Classes

8. Plasma Membrane Structure
Glycoproteins

9. Plasma Membrane Structure

10. Membrane Transport

11. Passive Transport Does not require energy from the cell
Substances move from an area of high concentration to an area of low concentration
Substances can move in both directions, depending on the concentration gradient

12. Examples of Passive Transport
Diffusion – the movement of a substance from an area of high concentration to an area of low concentration
Facilitated diffusion – same as above, but with the help of membrane proteins
Osmosis – the diffusion of water

13. Active Transport Does require energy from the cell
Substances move from an area of low concentration to an area of high concentration
Substances can move in only one direction, against the concentration gradient

14. Active Transport Example
Sodium/Potassium pump – a membrane protein that moves sodium out, while moving potassium in

15. Active Transport

16. Bulk Transport
Endocytosis
* Phagocytosis
* Pinocytosis

17. Bulk Transport
Exocytosis

18. Osmosis Solute – substance that is dissolved in a medium (solvent)
Solvent – substance (usually liquid) that
dissolves a solute
Solution – mixture of solutes dissolved in
a solvent
Osmotic pressure is created by the movement of water toward a higher solute concentration

19. Semipermeable membrane
Osmosis
Diffusion
Semipermeable membrane
Osmosis

20. Animal Cell Osmosis
Crenated

21. Plant Cell Osmosis
Turgor

22. Osmosis
Edema – the excess collection of extracellular fluids due to high solute concentration
Dehydration – the loss of extracellular fluids due to various causes