1. The Cell Membrane

2. Phospholipids Fatty acid Phosphate Phosphate head –hydrophilic Fatty acid tails –hydrophobic Arranged as a bilayer Aaaah, one of those structure–function examples “repelled by water”“attracted to water”

3. What passes the bilayer? polar hydrophilic heads nonpolar hydrophobic tails polar hydrophilic heads H2OH2O sugarlipidssalt waste impermeable to polar molecules

4. How do polar molecules cross? inside cell outside cell sugaraa H2OH2O salt NH 3

5. Why are proteins the perfect molecule for transport?

6. Classes of amino acids What do these amino acids have in common? nonpolar & hydrophobic

7. Classes of amino acids What do these amino acids have in common? polar & hydrophilic I like the polar ones the best!

8. Protein domains anchor molecule Polar areas of protein Nonpolar areas of protein

9. NH 2 H+H+ COOH Cytoplasm Retinal chromophore Nonpolar (hydrophobic)  -helices in the cell membrane H+H+ Porin monomer  -pleated sheets Bacterial outer membrane proton pump channel in photosynthetic bacteria aquaporin = water channel in bacteria function through conformational change = protein changes shape Examples H2OH2OH2OH2O H+H+ H+H+

10. 10 Membrane Proteins

11. 11 Cholesterol What is the function of cholesterol? 11

12. Membrane carbohydrates Play a key role in cell-cell recognition –ability of a cell to distinguish one cell from another antigens –important in organ & tissue development –basis for rejection of foreign cells by immune system

13. 13 Let’s go to the video Let’s go to the videoLet’s go to the videoLet’s go to the video

14. Any Questions??