1. Why is the cell membrane so important???

3. Names! Cell membrane Plasma membrane Selectively permeable membrane Semi permeable membrane

4. Functions of the Cell Membrane Protects the cell Regulates what goes in and out of cell Helps to communicate with other cells Creates attachments between cells Dynamic! **Maintains HOMEOSTASIS in the cell**

5. Structure of the Cell Membrane Phospholipid bilayer – double layered sheet – Properties of the lipids determine the properties of the membrane: Hydrophobic (“water- fearing”) = tails Hydrophilic (“water-loving”) cluster together = heads Heads DO touch water, tails DO NOT touch water

7. Fluid Mosaic Model dev. By Singer & Nicolson 1972 Proteins move within layers of lipids w/I viscous fluid –Transport –Structure Hydrogen bonds can form between water and phospholipid heads inside and outside of cell

8. Types of Membrane Proteins Glycoproteins Receptor proteins Recognition proteins Enzymatic proteins Attachment proteins Transport proteins *KNOW THE FUNCTIONS! (pg. 84 in textbook)*

9. The more double bonds there are in the tails the more fluid the membrane Incr. in temp. causes membr. To be more fluid (because mol. Move faster) Decr. Temp. (mol. Move slower -> less fluid)

12. Selectively Permeable Some substances can pass, others cannot pass – Most substances can pass – Substances that are too big or charged cannot cross the bilayer Therefore, cells need different means of TRANSPORT to move these substances into and out of the cell

13. REVIEW

14. (review slide)

15. REVIEW Head region of the lipid are polar molecules so they are attracted to water Tails region of the lipid are nonpolar they repel water. These molecular properties form the separation of inside and outside the cell.

16. Vocabulary Terms Solution- mixture in which one or more substances are UNIFORMLY distributed in another. “ homogenous solution ” Solute- what gets dissolved. Solvent- what does the dissolving. Ex. salt water: –salt is solute –water is solvent. Ex. Ice tea –Mix is solute –Water is solvent

17. Passive Transport Requires NO energy!! Movement from a high concentration to a low concentration!

18. Passive Transport 1. diffusion 2. osmosis 3. facilitated diffusion 4. diffusion through ion channels

19. Diffusion

20. Individual particles continuously move in random directions Molecules moving from a greater concentration to a lower concentration Ex: perfume, air freshener Simple diffusion – substances pass through the membrane with no outside aid –Ex. substances: Oxygen, Carbon Dioxide, water and lipid soluble molecules

21. Diffusion O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 Outside cellinside cell High Concentration Low Concentration Molecules are in constant motion they will continue to move until equilibrium is reached. Equilibrium ! Diffusion video: http://highered.mcgraw- hill.com/sites/00724958 55/student_view0/chapt er2/animation__how_dif fusion_works.html http://highered.mcgraw- hill.com/sites/00724958 55/student_view0/chapt er2/animation__how_dif fusion_works.html

22. Vocabulary Concentration gradient : difference in concentrations (amount of solute) Equilibrium : particles/molecules are equal on both sides of membrane

23. More diffusion -> “equilibrium”!!

24. Describe how oxygen and carbon dioxide move into and out of the lungs and extremities. Page 4 molecular workbench “diffusion, osmosis, active transport”

25. Osmosis

26. Diffusion of WATER from a high concentration to a low concentration across the cell membrane Water moves DOWN its concentration gradient until equilibrium is reached http://highered.mcgraw- hill.com/sites/0072495855/student_view0/chapter2/a nimation__how_osmosis_works.html

27. membrane watersugar solution There are as many water molecules on the right as there are on the left but many of them are attached to sugar molecules and are not free to move. 6

28. Because there are more freely moving water molecules on the left, more diffuse through the pores of the membrane from left to right than from right to left. 7 Molecular movement

29. Iso – Hyper – Hypotonic Solutions

30. Vocabulary Isotonic: concentration inside and outside of cell are the same  no net diffusion Hypertonic: when concentration of solute outside of cell is greater, water moves out of cell (shrink) (High solute, Low water) Hypotonic: concentration of solute inside of cell is greater, water moves into cell (burst) (Low solute, High water)

31. There is a greater concentration of free water molecules outside the cell than inside so water diffuses into the cell by osmosis and the cell swells up Osmosis in animal cells 11

32. Where is there more water? Which way will it move? Type of Solution? Out of the cell Into the cell Hypotonic Solution

33. Where is there more water? Which way will it move? Type of Solution? Equal No net movement Isotonic Solution

34. Where is there more water? Which way will it move? Type of Solution? In the cell Out of the cell Hypertonic Solution

35. Plasmolysis

36. Plants! Plasmolysis = cell shrinks away from cell wall due to water loss ex: drought (low rain fall) causing plants to wilt Turgid: swollen Turgor pressure the rigidity of plant cells when they contain enough water so that the cell membrane exerts pressure on the cell wall. Can tell turgor pressure is low when plant wilts

37. Osmosis: the diffusion of water as seen in class. Size of a cell membrane can change as the amount of water inside changes in response to external conditions change. Cells surrounded by “plain water” Cells surrounded by “salt” water

38. Facilitated Diffusion

39. Uses specific protein pores in the cell membrane to move certain “large” molecules from high concentration to low concentration. Used for transport of water soluble molecules (hydrophillic). Ex: ions, amino acids (small proteins), and sugars Carrier Protein - protein recognizes substance- >changes shape->delivers substance to inside of the cell Aquaporins – allow water to cross at a fast rate via faciliated diffusion http://highered.mheducation.com/sites/0072495855/stude nt_view0/chapter2/animation__how_facilitated_diffusion_ works.html

40. Ion Channels

41. Ion channels Allows ions Ca 2+ and Cl - to enter cell Some are open all the time Others are gated and will open when –Cell membrane stretches –Electrical signals –Chemical signals

42. Active Transport REQUIRES ENERGY! Movement from a LOW concentration to a HIGH concentation!

43. Active Transport 1. Sodium Potassium Pump 2. Endocytosis 3. Exocytosis

44. Active Transport

45. Sodium Potassium Pump pumps to keep ions in balance 3 Na+ out for every 2 K+ in This creates a build up of Na+ outside cell and K+ inside cell forming a net electrical charge across the membrane Allows for nerve impulses Contraction of muscles 1/3 of all energy in animal cells goes to running this pump even as we sleep!

46. Endocytosis

47. Take in external fluid, macromolecules and other large particles. Forms “vesicle” some fuse with lysosomes (digestion) others fuse with membrane of other organelles. 2 Types: a) pinocytosis – cell drinking fluid b) phagocytosis – cell eats

48. Exocytosis opposite of endocytosis!!