1. Cell Transport

2. Cell Membrane Cell membrane Semi – permeable Phospholipid bilayer
Polar hydrophilic (water – loving) head
Point outward/inward towards water
2 nonpolar hydrophobic (water – fearing) fatty acid tails
Tails point inward away from the water
Animal cells also have sterols (type of lipid)
Firm membrane and prevents freezing

3. Membrane Proteins Found within the lipid bilayer
Cell – surface marker
Glycoprotein identifies cell
Receptor protein
Recognizes and binds substances outside of cell
Transport protein
Helps substances move across the membrane
Enzyme
Assists in chemical reaction inside the cell

4. Enzyme

5. Cell Communication Chemicals in blood stream
Receptor protein responds to signal molecule
Permeability change
Enzyme activation
Second messenger

6. Homeostasis Transport of materials across the membrane
Passive transport
Active transport
Transport proteins
Channel
Carrier

7. Passive Transport Diffusion
Movement of molecules from high concentration to low concentration
Kinetic energy
Equilibrium
No energy needed

8. Diffusion Across the Membrane
Simple diffusion
Move freely across the membrane
Small nonpolar molecules (O2 and CO2)

9. Facilitated Diffusion
Aid in the movement of molecules across the membrane
Carrier proteins
Channel proteins
Specific ions or molecules
Osmosis
Diffusion of water molecules
Polar molecules so channel proteins are used

10. Osmosis Explained
Solution is made up of solute (ex. sugar) and solvent (liquid).
Flow of water molecules depends on the concentration of the solutes on both side of the cell membrane

11. 3 Solutions
Hypotonic
Hypertonic
Isotonic

12. Hypotonic Solute (sugar) is lower outside of the cell than inside
Water moves into the cell
Cytolysis

13. Hypertonic Solute is higher outside of the cell than inside
Water moves out of the cell
Plasmolysis

14. Isotonic Solute is equal inside and outside of cell
Equal movement of water molecules

15. Carrier Protein

16. Carrier Protein Molecule binds to specific protein
Protein changes shape
Shields molecule from hydrophobic interior of cell membrane
Releases molecule on other side
Protein returns to original shape

17. Active Transport Requires energy from the cell
Moves material against the concentration gradient (upstream)
Cell membrane “pumps” (Carrier Proteins)
Vesicles

18. Sodium – Potassium Pump

19. Vesicles
Endocytosis

20. Exocytosis