1. Cell Membrane

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

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

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

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

6. Passive Transport Requires NO energy
Goes down its “concentration gradient”
3 types – 1) diffusion, 2) osmosis, 3) facilitated diffusion

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

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

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

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

11. Three main types of active transport
movement directly across the cell membrane with assistance from transport proteins
EX: sodium-potassium pump
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

12. Sodium potassium pump

13. 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
Phagocytosis solid particles taken into the cell

14. 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.