1. Cell Membrane

2. Cell membrane A gateway and a barrier for the cell. Controls what enters & exits A gateway and a barrier for the cell. Controls what enters & exits composed of phospholipids and proteins. composed of phospholipids and proteins.

3. Phospholipids Made up of a polar head and a nonpolar tail. Made up of a polar head and a nonpolar tail. Head – water loving Head – water loving Tails – water hating Tails – water hating Tails stay to inside of bi-layer to avoid contact with water. Tails stay to inside of bi-layer to avoid contact with water. Polar Nonpolar Lipid Bilayer:

4. Proteins Marker Proteins – attach to carbohydrates on cell surface that identifies cell type. Marker Proteins – attach to carbohydrates on cell surface that identifies cell type. Receptor Proteins – recognize and bind to specific substances outside the cell Receptor Proteins – recognize and bind to specific substances outside the cell

5. Transport Proteins –helps substances move across the membrane. Transport Proteins –helps substances move across the membrane.

6. Osmosis diffusion of water across cell membranes diffusion of water across cell membranes NO ENERGY REQUIRED NO ENERGY REQUIRED Ex: lysing of a blood cell. Ex: lysing of a blood cell.

7. Diffusion net movement of molecules from a region of high concentration to a region of lower concentration net movement of molecules from a region of high concentration to a region of lower concentration With the “concentration gradient” With the “concentration gradient” NO ENERGY REQUIRED NO ENERGY REQUIRED Ex: perfumes from a Ex: perfumes from a bouquet spreads bouquet spreads across room across room

8. Facilitated Diffusion the diffusion of a substance moving with the concentration gradient, but which require the assistance of other molecules. the diffusion of a substance moving with the concentration gradient, but which require the assistance of other molecules. NO ENERGY REQUIRED NO ENERGY REQUIRED The “facilitation” is physically turning a molecule so that it may more easily pass through a membrane The “facilitation” is physically turning a molecule so that it may more easily pass through a membrane

9. Active Transport movement of molecules from a region movement of molecules from a region of low concentration to a region of high concentration. of low concentration to a region of high concentration. This is against the “concentration gradient” This is against the “concentration gradient” Requires Requires ENERGY!!! ENERGY!!!

10. Two main types of active transport movement directly across the cell membrane with assistance from transport proteins movement directly across the cell membrane with assistance from transport proteins EX: sodium-potassium pump EX: sodium-potassium pump helps nerve cells to pass their signals in the form of electrical impulses helps nerve cells to pass their signals in the form of electrical impulses maintain a higher concentration of potassium ions inside the cells compared to outside, and a higher concentration of sodium ions outside of cells compared to inside maintain a higher concentration of potassium ions inside the cells compared to outside, and a higher concentration of sodium ions outside of cells compared to inside

11. Sodium potassium pump

12. Two main types of active transport endocytosis - is an infolding and then pinching in of the cell membrane so that materials are engulfed into a vacuole or vesicle within the cell endocytosis - is an infolding and then pinching in of the cell membrane so that materials are engulfed into a vacuole or vesicle within the cell Phagocytosis solid particles taken into the cell Phagocytosis solid particles taken into the cell

13. Two main types of active transport Exocytosis – substances are released from the cell through a vesicle that transports the substance to the cell surface and then fuses with the membrane to let the substance out of the cell. Exocytosis – substances are released from the cell through a vesicle that transports the substance to the cell surface and then fuses with the membrane to let the substance out of the cell.