1. Warm-Up
Name the three basic parts of a cell and describe the functions of each.
Why do phospholipids organize into a bilayer – tail-to-tail – in a watery environment?

2. Hypertonic, isotonic, or hypotonic?
Warm-Up
Hypertonic, isotonic, or hypotonic?
What type of fluid might be infused into the bloodstream of a patient who needs fluid drawn out from swollen tissues?
What type of fluid might be used (carefully) to rehydrate the tissues of extremely dehydrated patients?
In a U-tube separated by a selectively permeable membrane, there is .2 M glucose in Side A, and .4 M glucose in Side B. Side A is ____ compared to Side B, and Side B is ____ compared to Side A.
If the membrane in #3 is only permeable to water, what will happen?

3. Part 2: Membrane Transport
Chapter 3: Cells
Part 2: Membrane Transport

4. Membrane transport

5. Membrane transport Interstitial fluid: Fluid outside cells
Rich, nutritious “soup” – amino acids, sugars, fatty acids, vitamins, hormones, salts, wastes
Selective Permeability:
Plasma membrane only allows some substances to enter cell
Nutrients in, wastes out
By passive or active transport

6. Passive transport No energy (ATP) needed
Molecules move down concentration gradient from HIGH  LOW concentration
Types: diffusion, filtration

7. Simple diffusion
Nonpolar & lipid-soluble substances diffuse directly through lipid bilayer
Eg. O2, CO2, fat-soluble vitamins

8. Facilitated diffusion
Transport proteins (carrier or channel proteins) assist molecules across membrane
Eg. glucose, amino acids, H2O, ions

9. Channel proteins
Water-filled channels
Eg. ions

10. Carrier proteins
Binds to molecule, changes shape, ferries it across membrane
Eg. glucose transporter

11. osmosis
Diffusion of H2O
Aquaporins: channel proteins for H2O passage

14. Tonicity
Ability of solution to change shape or tone of cells by changing water volume
Isotonic = equal concentration solutes
Hypertonic = higher conc. of solutes
Hypotonic = lower conc. of solutes

15. Effect of solutions on red blood cells

16. RBC’s in isotonic & hypertonic solutions

17. Active transport Energy (ATP) is needed!!
Move molecules against concentration gradient from LOW  HIGH concentration
Types: Primary and Secondary

18. Primary Active Tranport
Directly uses ATP to drive transport
Eg. Ca2+ pump, H+ pump, Na+-K+ pump

19. Sodium-Potassium Pump

20. Secondary active transport
Move more than 1 substance at a time
Symport: 2 substances moved in same direction
Antiport: 2 substances cross in opposite directions
Eg. cotransport of sugars, animo acids, ions

21. Secondary active transport: Na+/Glucose Cotransport

22. Vesicular transport
Fluid & large particles transported across membranes in vesicles (sacs)
Exocytosis: “out of cell” – eject substances
Endocytosis: “within the cell”- ingest substances

23. Types of endocytosis
Phagocytosis: (cell eating) – engulf large or solid material
eg. WBC engulf bacteria

24. Types of endocytosis
Pinocytosis: (cell drinking) – fluid w/dissolved molecules
Eg. intestinal cells

25. Types of endocytosis
Receptor-mediated endocytosis: concentrate specific substances (ligands) that bind to receptor proteins
Eg. insulin, iron, cholesterol