1. The Cell Membrane

2. Animal Cell

3. Plant Cell

4. Prokaryotic Cell: Bacteria

5. Important Facts  Lipid bi-layer  Embedded proteins  Encloses the cytoplasm  Organelles and Cytosol (liquid)  Separates inside of cell from outside environment  Semi-Permeable  Controls what enters and leaves the cell  Allows some things in and keeps others out  Also known as “plasma membrane”

6. Cell Membrane Structure  Fluid-like structure  Not stiff or rigid  Phospholipids and proteins can drift/move around  Proteins form patterns that look like a mosaic  Fluid Mosaic Model  Current description for the membrane

7. Cell Membrane Structure

8.  Bi-layer made up of lipids and proteins  Phospholipids  Special lipids made of one glycerol, two fatty-acids and a phosphate

9. Phospholipid Structure

11. Properties of Water Review  Water is a polar molecule  Partially positively charged (hydrogen)  Partially negatively charged (oxygen)  Water molecules are attracted to other molecules - + + So polar molecules stick together and repel away non-polar molecules

12. Properties of Water Review Since water is a polar molecule the opposite charges on other molecules help them stick together!!

13. Phospholipid Structure  “Polar Heads”  Hydrophilic  “water loving”  Phosphate part is attracted to water  Polar heads point to watery parts of the cell  Cytoplasm  Outside Environment

14. Phospholipid Structure  “Non-Polar Tails”  Hydrophobic  Doesn’t like water  Fatty-acids (lipid) repels water  Non-Polar tails point towards each other in the center of the membrane  Between the two layers

15. Bi-Layer Arrangement  The cytoplasm of the cell is an “aqueous” or “watery” environment.  How do the phospholipids arrange themselves? Remember….hydrophilic and hydrophobic areas.

16. Bi-Layer Arrangement HydrophilicHydrophobic

17. Bi-Layer Arrangement Hydrophilic Hydrophobic

18. Membrane Proteins  Transmembrane Proteins  Embedded in the cell membrane  Exposed to both the inside and outside of the cell  Peripheral Proteins  Attached to the external or internal surface of the membrane  Channel Proteins  Help move materials into and out of the cell  Cell Markers  Carbohydrate chains that identify cell types  Enzymes  Assist in chemical reactions  Speed up and lower activation energy

19. Membrane Proteins Transmembrane Protein Peripheral Protein Channel Protein Cell Marker Protein

21. Outside of cell Inside of cell (cytoplasm) Cell membrane Proteins Protein channel Lipid bilayer Carbohydrate chains Section 7-3 Figure 7-12 The Structure of the Cell Membrane The Cell Membrane