Cell Membrane

1. Cell Membrane

2. What cells have a cell membrane… • ALL cells have a cell membrane! • Prokaryotic and Eukaryotic

3. Cell Membrane’s Job… • Forms a boundary between a cell and the outside environment • Controls the passage of materials into and out of a cell

5. What is the cell membrane made of? • A double layer of phospholipids • Hydrophilic Heads-”water loving”-are exposed to water inside and outside the cell • Hydrophobic Tails-”water fearing”-cannot be exposed to water

6. Phospholipid

7. The cell membrane also has… • Molecules embedded within the phospholipid layers • Cholesterol molecules-provide strength for membrane • Proteins-help materials cross the membrane • Carbohydrates-attach to membrane proteins and serve as identification tags

8. cell membrane Cell Membrane Structure carbohydrate chain protein cholesterol protein protein channel

9. Fluid Mosaic Model • Describes the arrangement of the molecules that make up the cell membrane • Cell membrane is flexible, not rigid. • The phospholipids in each layer can move from side to side and slide past each other. http://youtu.be/Rl5EmUQdkuI

10. Property of the Cell Membrane • Selective Permeability (semipermeable) • Cell membrane allows some, but not all, materials to cross into or out of the cell. • Enables cell to maintain homeostasis

11. Concentration-number of particles present in a solution Which side, outside or inside, has the highest/lowest concentration?

12. How do molecules move across the cell membrane? • Several different ways molecules will move. • Some ways require the cell to use energy and some do not. • How a molecule moves across the membrane depends on: • Size • Polarity • Concentration inside the cell vs. outside the cell

13. Examples of materials moving across the cell membrane… • Small nonpolar molecules move easily across the membrane • Small polar molecules are transported via proteins • Large molecules are moved in vesicles