CELL BIOLOGY - Overview: A. Membranes - how stuff get in/out of cells 1. Structure

2. CELL BIOLOGY - Overview: A. Membranes - how stuff get in/out of cells 1. Structure 2. Functions

3. CELL BIOLOGY - Overview: A. Membranes - how stuff get in/out of cells 1. Structure 2. Functions 3. Types of "transport"

4. Types of "transport" - DIFFUSION LE 7-11a Molecules of dye Membrane (cross section) WATER Net diffusion Net diffusion Equilibrium Diffusion of one solute

5. Types of "transport" - DIFFUSION LE 7-11b Net diffusion Net diffusion Equilibrium Equilibrium Net diffusion Net diffusion Diffusion of two solutes

6. Lower concentration of solute (sugar) Higher concentration of sugar Same concentration of sugar LE 7-12 H2O Selectively permeable mem- brane: sugar mole- cules cannot pass through pores, but water molecules can - OSMOSIS: diffusion of water across a semi-permeable membrane from HI to LO water potential Water Potential: as solute conc. increases as pressure increases Osmosis

7. Isotonic solution Hypertonic solution Hypotonic solution Animal cell 9% 15% LE 7-13 H2O H2O H2O H2O 1% 9% Salt 9% Salt 9%Salt Shriveled Normal Lysed Plant cell H2O H2O H2O H2O Flaccid Plasmolyzed Turgid (normal)

8. Types of "transport" - FACILITATED DIFFUSION - for big or charged stuff LE 7-15a EXTRACELLULAR FLUID Solute Channel protein CYTOPLASM movement in the direction of the concentration gradient

9. Types of "transport" - FACILITATED DIFFUSION - for big or charged stuff LE 7-15b Carrier protein Solute movement in the direction of the concentration gradient

10. Types of "transport" - ACTIVE TRANSPORT AGAINST concentration gradient MUST use ENERGY Makes cell DIFFERENT FROM the environment. LE 7-17b ATP

11. EXTRACELLULAR FLUID Na+ [Na+] high [K+] low Na+ Na+ Na+ Na+ LE 7-16 Na+ Na+ Na+ ATP [Na+] low [K+] high P P Na+ CYTOPLASM ADP Phosphorylation causes the protein to change its conformation, expelling Na+ to the outside. Na+ binding stimulates phosphorylation by ATP. Cytoplasmic Na+ bonds to the sodium-potassium pump K+ K+ K+ K+ K+ P K+ P K+ is released and Na+ sites are receptive again; the cycle repeats. Loss of the phosphate restores the protein’s original conformation. Extracellular K+ binds to the protein, triggering release of the phosphate group.

12. Passive transport Active transport LE 7-17 ATP Facilitated diffusion Diffusion

13. – EXTRACELLULAR FLUID + LE 7-18 – ATP + H+ H+ Proton pump H+ – + H+ H+ – + CYTOPLASM H+ – +

14. – + H+ ATP H+ – LE 7-19 + Proton pump H+ H+ – + H+ – + H+ Diffusion of H+ Sucrose-H+ cotransporter H+ – + – + Sucrose

15. Types of "transport" - Phagocytosis and Pinocytosis LE 7-20a PHAGOCYTOSIS CYTOPLASM EXTRACELLULAR FLUID 1 µm Pseudopodium Pseudopodium of amoeba “Food” or other particle Bacterium Food vacuole Food vacuole An amoeba engulfing a bacterium via phagocytosis (TEM)

16. Types of "transport" - Phagocytosis and Pinocytosis LE 7-20b PINOCYTOSIS 0.5 µm Plasma membrane Pinocytosis vesicles forming (arrows) in a cell lining a small blood vessel (TEM). Vesicle

17. RECEPTOR-MEDIATED ENDOCYTOSIS Coat protein LE 7-20c Coated vesicle Receptor Coated pit Ligand A coated pit and a coated vesicle formed during receptor- mediated endocytosis (TEMs). Coat protein Plasma membrane 0.25 µm