1. Introduction to Cell Membranes and Transport

2. PHOSPHOLIPIDS
Polar / Hydrophillic head and Nonpolar / Hydrophobic tail! Amphipathic (literally “dual-sympathy”
= Glycerol linked to phosphate group and two fatty acid chains

3. PHOSPHOLIPIDS
Polar / Hydrophillic head and Nonpolar / Hydrophobic tail! Amphipathic (literally “dual-sympathy”)

4. PHOSPHOLIPID BILAYERS
ARE SELECTIVELY PERMEABLE! Very small molecules, especially nonpolar molecules like 02 will be able to get across easily  macromolecules, ions cannot get across without help!

5. Variation in Membrane Fluidity: Bond Saturation
Can pack saturated more tightly = increased hydrophobic interactions; also longer the tail = increased hydrophobic interactions

6. Variation in Membrane Fluidity: Bond Saturation

7. Atherosclerosis

8. Variation in Membrane Fluidity: Cholesterol

9. THE CELL MEMBRANE IS SELECTIVELY PERMEABLE!

10. Facilitated Diffusion
Types of Transport:
Diffusion
Osmosis
Facilitated Diffusion
Active Transport
What is moving?
Concentration gradient?
Energy?
Proteins?

11. Osmosis

12. Plant Cells Are Complicated…

13. Water Potential Water Potential =
Quantification of the tendency of water to diffuse from one area to another
w.p. = the potential energy that water has in a particular environment compared with the potential energy of pure water at room temp and atmospheric pressure; under these conditions, pure water has a water potential of 0 water flows from areas of high water potential to areas of lower water potential; Greek letter sigh; measured in bars

14. Water Potential Solute Potential ( ) =
As solute potential goes up, water concentration goes down, there are fewer water molecules to diffuse, so water potential must go down; solute potential must be either zero (for pure water), or negative, if the water contains a solute
Solute Potential ( ) =

15. Water Potential Pressure Potential ( ) =
Force exerted by the wall is called wall pressure; as water moves into the cell, the pressure inside the cell known as turgor pressure, increases until wall pressure is induced. Cells that are firm and that experience wall pressure are said to be turgid; pressure potential = any pressure on water; measured in megapascals (Mpa) car tire = 0.2MPa, and 0.2 and 0.3 MPa
Pressure Potential ( ) =

16. Water Potential: The Soil
Can also think about water potential of leaves, stem, roots, soil and air: in soil – water contains fewer solutes than water in roots of plants; soil has higher potential in soil than in roots (exceptions: very dry soils, salty soils)

17. Water Potential and Potatoes

18. Design an Experiment to Test the Effect of _________ on Diffusion / Osmosis
Hot plate
Water bath
Sucrose solutions
Salt
Starch
Cork Borer
Potatoes
Chicken