2. 2007-2008 The Cell Membrane

3. What does the cell membrane do? Separates living cell from aqueous environment Controls traffic in & out of the cell –allows some substances to cross more easily than others –What types of molecules flow easily through the cell membrane? Which need “help”?

4. What are these structures? What are their properties? polar hydrophilic heads nonpolar hydrophobic tails polar hydrophilic heads H2OH2O sugar lipids salt CO 2 Impermeable to polar molecules Permeable to non-polar

5. How do polar molecules get through? Membrane becomes semi-permeable via channels –specific channels allow specific material across cell membrane inside cell outside cell sugaraa H2OH2O salt NH 3

6. 2007-2008 Why are proteins the perfect molecule to build structures in the cell membrane? Which macromolecle is the perfect molecule to build structures in the cell membrane?

7. What do these amino acids have in common? nonpolar & hydrophobic

8. polar & hydrophilic What do these amino acids have in common?

9. Where are the hydrophobic AA’s and where are the hydrophilic AA’s?

10. Many Functions of Membrane Proteins Outside Plasma membrane Inside Transporter Cell surface receptor Enzyme activity Cell surface identity marker Attachment to the cytoskeleton Cell adhesion “Antigen” “Channel”

11. Extracellular fluid Cholesterol Cytoplasm Glycolipid Transmembrane proteins Filaments of cytoskeleton Peripheral protein Glycoprotein Phospholipids