1. Cell Membranes and Transport 1-2- Water and Polarity 1-3 – Acids, Bases and Buffers 1-4 – Biological Molecules: Lipids 1-5 – Cell Membranes 1-6 – Surface Area-Volume Ratio

2. The unique properties of water make life as we know it possible. Transport across membranes is just one process in our bodies that is greatly affected by WATER.

3. Water and It’s role in biological Systems describe how the polarity of the water molecule results in hydrogen bonding

4. Polar bonding Unequal sharing of electrons  (+) and  (-) charges on the molecule

5. Polarity creates Hydrogen bonds H bonds are relatively weak Animation of Covalent and Polar bonds (scroll down on the page when it opens) Animation of Covalent and Polar bonds (scroll down on the page when it opens)

6. There’s strength in numbers!

7. Unique Properties of Water describe the role of water as a solvent, temperature regulator, and lubricant 1. “Universal Solvent” Dissolves all polar and ionic molecules.

8. Hydrophobic Vs Hydrophilic?

9. Hydrophobic Interactions: Oil cannot interact with the polar regions of H 2 O and actually interfere with the H bonds between H 2 O molecules. interfering(breaking) with the H bonds requires ENERGY When given the chance, oil droplets will cluster, reducing the surface area exposed to the H 2 O. (therefore using less ENERGY to break the H bonds) *** the H Bonds “force” the oil droplets to stay together.

10. 2. Temperature Regulation by Water --another process our bodies use water for! 1. High specific heat (the amount of Energy needed to raise 1gm of water 1 o C) 2. High heat of vaporization 3. High heat of fusion “Water is Life” – Mr. Anderson with Bozeman science.

11. Acids, Bases and pH differentiate among acids, bases, and buffers pH measures the [ ] of the H+ compared with OH- PURE H 2 O : Neutral, therefore pH 7 [H+] = [OH-] ** the pH scale is a log scale; a change in pH from 7 to 6 means there are 10x more H+ ions than in the neutral solution.

12. Acids Dissociate to donate H + ions pH < 7 [H + ] > [OH - ]

13. Bases molecules that release OH- ions therefore pH > 7 (ex. NaOH) [H+] < [OH-]

14. Controlling pH in the Body BUFFERS are molecules that can either pick up or release hydrogen (or hydroxide) ions Eg. pH is too low: HCO 3 - + H + --> H 2 CO 3 (bicarbonate) (carbonic acid) pH is too high: H 2 CO 3 + OH - HCO 3 - + H 2 O (excess of OH-)

15. Cell Membranes “gate keepers” 1. Isolate from outside 2. Control entry and exit 3. Communicate with others 4. Bare identification (I’m one of you!) you tube cell membranes (lots of other links for passive/active transport, etc

16. Cell Walls NB** Cell walls are different from cell membranes Stiff, non-living Made of complex carbohydrates Cellulose for plants Chitin for fungi Chitin-like frame for bacteria Used for support and protection Very porous; entry only controlled by size

17. Which of these statements are true comparing cell walls with membranes? WallsMembranes ANon-livingLiving BPlants and bacteria only Animals only CControl entrance by size only Control entrance by many factors DMade with celluloseMade with lipids EContain pores

18. Fluid Mosaic Model A phospholipid bilayer with proteins scattered through it “fluid” because the proteins seem to “float” around the bilayer Hydrophilic heads on the outside Hydrophobic tails on the inside

19. PHOSPHOLIPIDS – one type of Lipid Watch Mr. Anderson – Bozeman Science on LIPIDS

20. Lipids Glycerol + Fatty Acids

21. Saturated fatty acids Unsaturated Fatty acids

23. Hydrophobic layer is a barrier to H 2 O soluble molecules (but makes it less fluid)

24. Cholesterol in the bilayer is even less permeable to H 2 O soluble molecules (but makes it less fluid)

25. “Protein Mosaic” Membrane proteins will interact with the hydrophobic and hydrophilic layers of the bilayer Some proteins will protrude into the cytoplasm, some into the extracellular space, others into both

26. Glycoproteins Membrane proteins that have a carbohydrate chain attached Often seen in proteins that protrude outside the cell

27. Glycolipids Membrane lipids that have a carbohydrate chain attached Both glycoproteins and glycolipids OFTEN function in cell-to-cell communication and/or recognition

28. What does the “fluid” in “fluid mosaic model” refer to? A. The structure of the cell membrane B. The structure of the cell wall C. The fact that the membrane is made up mostly of water D. The fact that the membrane is always changing, so it seems to be “fluid” E. The fact that the membrane is made up of lipids, and they tend to “flow”

29. What does “mosaic” mean? A. a picture B. a lipid C. a bunch of different things clumped together on a background D. a type of protein that lets things into the cell E. No idea!

30. Which of the following is not true regarding this diagram? A. 1a and 1b are fatty acids B. 3 is a phosphate group C. 5 is the hydrophobic end of the molecule D. 6 is the hydrophobic end of the molecule E. this is a type of lipid

31. Which one is a: 1. Phospholipid 2. Glycolipid 3. Cholesterol

32. 3 major membrane Protein Categories: 1. Transport proteins Regulated, fast method for specific molecules to enter and exit Channel proteins Carrier proteins

33. 2. Receptor Proteins When activated, set off enzymatic sequences inside the cell

34. 3. Recognition Proteins “identification tags”

35. Membrane Transport - RATE Depends on: Gradient (concentration, electrical or pressure) Size of molecule Lipid solubility # of transporters

36. Diffusion The random net movement of molecules from an area of high concentration to an area of low concentration. (this is following the “concentration gradient”)

37. Osmosis The diffusion of WATER across a selectively permeable membrane (this is also following the “concentration gradient” and does not require energy)

38. Osmotic Effects Isotonic solution Same solute concentration Cell is happy (no net loss or gain of water)

39. HYPERtonic solutions [Solute] is greater outside the cell than inside the cell Cell is not happy It will crenate (shrink)

40. HYPOtonic solutions Solute concentation is less outside the cell than inside Cell is not happy Cell will lyse

42. Why are cells so small? (why don’t we grow them larger?) animation that shows comparison of SA and Volume animation that shows comparison of SA and Volume calulating SA/V ratios WS calulating SA/V ratios WS (that crazy guy with the pink shirt/yellow tie explains SA/Vol ratio)

43. Active transport Often against the concentration gradient Therefore, REQUIRES ENERGY (ATP --> ADP + P) Uses transporter proteins

44. Endocytosis - 3 types

45. Phagocytosis Large particles

46. 2. Pinocytosis Liquid and smaller particles only

47. Receptor-mediated Endocytosis Uses receptors to bind first to the desired molecules, then gathers them together before enclosing them in a membrane