1. Aim: How cell membrane organized?
HW #10
1. Complete the handout on the cell
Do now: You have 5 min.
Explain how the following structures:
Nucleolus
Ribosomes
Endoplasmic reticulum
cytoplasm

2. The Plasma Membrane *

3. Photograph of a Cell Membrane*

4. I. Cell Membrane A. General
1. Flexible and allows a unicellular organism to move

5. Maintain a high concentration of materials in the cell.
The Plasma Membrane
4/6/2017
B. Function
Maintain a high concentration of materials
in the cell.
2. Keep harmful materials out.
3. Control the movement of materials into
and out of the cell.
4. Let the cell sense its environment.
G. Podgorski, Biol. 1010

6. 5. Protective barrier
6. Regulate transport in & out of cell (selectively permeable)
7. Allow cell recognition
8. Provide anchoring sites for filaments of
cytoskeleton

7. Membrane Components The Plasma Membrane 4/6/2017
G. Podgorski, Biol. 1010

8. Proteins Are Critical to Membrane Function
The Plasma Membrane
4/6/2017
Proteins Are Critical to Membrane Function
G. Podgorski, Biol. 1010

9. 9. Provide a binding site for enzymes
10. Interlocking surfaces bind cells together
11. Contains the cytoplasm (fluid in cell)

10. C. Maintains homeostasis
Balanced internal condition of cells.
Also called equilibrium
Maintained by plasma membrane controlling what enters & leaves the cell.

11. Review
Explain what would happen to a cell if the cell
membrane did not do its job properly.

12. D. Structure of the Cell Membrane*

13. Proteins (peripheral & integral)
The Plasma Membrane
The Plasma Membrane *
1. Membrane Components
Phospholipids
Proteins (peripheral & integral)
Cholesterol
Carbohydrates (glucose)
G. Podgorski, Biol. 1010
G. Podgorski, Biol. 1010 *

14. a. Phospholipids 1. Make up the cell membrane
a. Contains 2 fatty acid chains that are nonpolar
b. Head is polar & contains a –PO4 group *

15. Figure 04.UN00a
Title:
A phospholipid
Caption:
A phospholipid.

16. Figure 04.UN00b
Title:
A phospholipid
Caption:
A phospholipid bilayer.

17. Figure 04.3a
Title:
Diffusion through the plasma membrane
Caption:
Simple diffusion through the phospholipid bilayer: Gases such as oxygen and carbon dioxide and lipid-soluble molecules can diffuse directly through the phospholipids.

18. Figure 04.1
Title:
The plasma membrane is a fluid mosaic
Caption:
The plasma membrane is a bilayer of phospholipids in which various proteins are embedded. Many proteins have carbohydrates attached to them, forming glycoproteins. The wide variety of membrane proteins fall mostly into three categories: transport proteins, receptor proteins, and recognition proteins.

19. The Plasma Membrane
The Plasma Membrane
FLUID MOSAIC MODEL *
1. FLUID- because individual phospholipids and proteins can move around freely within the layer, like it’s a liquid.
2. MOSAIC- because of the pattern produced by the scattered protein molecules when the membrane is viewed from above.
G. Podgorski, Biol. 1010
G. Podgorski, Biol. 1010 *

20. Cell Membrane
Polar heads are hydrophilic “water loving”
Nonpolar tails are hydrophobic “water fearing”
Makes membrane “Selective” in what crosses

21. The Plasma Membrane G. Podgorski, Biol. 1010 The Plasma Membrane *

22. Cell Membrane Hydrophobic molecules pass easily; hydrophillic DO NOT
The cell membrane is made of 2 layers of phospholipids called the lipid bilayer

23. Solubility
Materials that are soluble in lipids can pass through the cell membrane easily

24. Semipermeable Membrane
Small molecules and larger hydrophobic molecules move through easily.
e.g. O2, CO2, H2O *

25. Semipermeable Membrane
Ions, hydrophilic molecules larger than water, and large molecules such as proteins do not move through the membrane on their own. *