1. The Cell Membrane

3. How did scientists figure out
the bilayer structure?
Gorter & Grindle
Studied Red Blood Cells
(RBC)

5. Isolated RBC ghosts
(RBC + H20---- burst….
get just membrane)
2. Removed lipids from ghost
3. Measured whole RBC
(surface area)
4. Lipids float to surface
5. Measure surface area lipids
covered

6. Conclusion
Lipids from the Membrane
Covered 2X the area
Compared to the whole RBC

10. Passive Transport
Transport across a membrane when molecules move due to a concentration gradient….from high to low concentration. Due to the pressure to move, molecules spread out, no cellular energy is required.

11. Examples: Osmosis Facilitated diffusion Endocytosis: Phagocytosis
Pinocytosis
Receptor Mediated Endocytosis

12. Active Transport
Transport across a cell membrane where molecules move from low concentration to high. This is against the concentration gradient. Molecules will be force to move the other direction, so energy is required by the cell.

13. Examples
Sodium-potassium Pump
Proton Pump