1. Read Chapter 5.
Today:
- membranes that line body cavities
- ***the cell membrane

2. Membranes in the body line a body cavity
or are between two compartments.

3. Why have a cell membrane?
- isolate the cell  cytosol (intracellular fluid) from extracellular fluid
- regulate exchange with the environment  ions, nutrients, wastes, secretions
- cell communicates with the environment  eg. receptor proteins bind signaling molecules
- structural support  cellular junctions, anchor cytoskeletal proteins

4. What are the components of the cell membrane
and what are their functions?

5. What are the components of the cell membrane and what are their functions?

6. Lots of phospholipids.

10. Integral mb proteins are tightly associated to mb
(eg. membrane spanning).
Associated protein is loosely bound to mb
(eg. enzymes, some structural).

11. An example of a membrane spanning protein.

12. Functions of membrane proteins:
1. Structural proteins (junctions, cytoskeleton)
3. Receptors – bind a signaling molecule (ligand)
2. Enzymes – reactions cell membrane (digestion, signaling)
4. Transporters
- channels - water filled pore
- carrier proteins - bind molecule to be carried across

13. 1. Structural proteins:junctions
Functions of membrane proteins:

14. 1. Structural proteins: cytoskeleton
Functions of membrane proteins:

15. 3. Enzymes 2. Cell membrane receptor protein
Functions of membrane proteins:

16. 3. Channel proteins are gated.

17. Gating of a channel protein:

18. How are the channels gated (opened)
How are the channels gated (opened)? Voltage gated, chemically gated, mechanically gated.

19. 4. Facilitated diffusion by a carrier protein:
- never a continuous pore

20. Facilitated diffusion by a carrier protein:

21. How can lipids enter a cell?

23. How can glucose enter a cell?

24. Facilitated diffusion by a carrier protein:G G G

25. How can calcium (Ca++) enter a cell?

26. Calcium enters through a calcium channel

27. How does insulin bind onto a cell?

28. Insulin receptor protein