1. AP Biology

2. Fluid Mosaic Model:  States that membranes are composed of a lipid bilayer containing various proteins and glycoproteins some of which are mobile while others are stationary

3. Fluid Mosaic Model:  Fluid?  molecules are continuously removed and replaced with newly made molecules  Can stretch  Can reseal itself

4. Fluid Mosaic Model:  Mosaic?  proteins embedded in or attached to a phospholipid bilayer

5. Fluid Mosaic Model:  Composed of?  1. Lipids  2. Proteins  3. Carbohydrates (glycoproteins, glycolipids)

6. Fluid Mosaic Model:  Lipids??  Phospholipids more specifically  Composed of:  Compounds with nitrogen  Phosphate group  Glycerol  Saturated and unsaturated fatty acid chains

8. Fluid Mosaic Model:  Amphiphathic molecule:

10. Fluid Mosaic Model:

11. Fluidity of Membranes:  membranes are not static  hydrophobic and hydrophilic interactions  proteins and lipids can drift, laterally in the membrane  temperature does play a role on membrane fluidity, permeability, enzyme activity  cholesterol  fluidity and function

12. Roles of Membrane  1.Containment and Separation  2. Material Exchange  3. Information Detection  4. Identification  5. Attachment reinforcement  6. Movement and Metabolism

13. Membrane Proteins and their Functions:  Proteins determine most of the membranes specific functions  Bound to cytoskeleton on cytoplasmic side and ECM on extracellular side

14. Membrane Proteins and their Functions:  Two major types of membrane proteins:  Integral  peripheral

15. Integral Proteins:  penetrate the hydrophobic core of the lipid bilayer  consists of one or more stretches of nonpolar amino acids  hydrophilic parts are exposed on either end of the bilayer

17. Peripheral Proteins:  not embedded in the membrane  loosely bound to the surface of the membrane  often bound to exposed parts of integral proteins

19. Functions of Membrane Proteins: 11. Transport 22. Enzyme activity 33. Cell to cell recognitions 44. Signal transduction 55. Intercellular joining 66. Attachment (cytoskeleton and ECM)

21. The Permeability of the lipid bilayer:  Hydrophobic molecules(hydrocarbons), CO2, O2  Dissolve in the membrane and pass with ease  polar, hydrophilic molecules such as ions  Have trouble passing through the membrane because of the hydrophobic core  Glucose, water(polar molecules)  Pass slowly through the membrane

22. The Permeability of the lipid bilayer:  Transport Proteins  Enhance the permeability of membrane  Substance specific  Span the width of the membrane  Two types:  Channel proteins  Carrier proteins

23. The Permeability of the lipid bilayer:  channel proteins:  having a hydrophilic channel  certain molecules and ions use to pass through the membrane  carrier proteins:  transmit molecules through the membrane by changing shape

24. Passive Transport:  Diffusion  the tendency for molecules of a substance to spread out evenly into the available space  Osmosis:  diffusion of water across a semi-permeable membrane

25. Passive Transport:  Facilitated Diffusion  passive diffusion of polar molecules and ions with the help of transport proteins  gated channels: need a stimulus to open((electrical or chemical stimulus)

26. Energy driven transport:  Active Transport:  using energy to move a substance against a concentration gradient  uses carrier proteins  energy is supplied by ATP  See sodium/ potassium pump

27.  http://highered.mcgraw- hill.com/sites/0072495855/student_view0/cha pter2/animation__how_the_sodium_potassiu m_pump_works.html http://highered.mcgraw- hill.com/sites/0072495855/student_view0/cha pter2/animation__how_the_sodium_potassiu m_pump_works.html

28. Bulk Transport  Passing through membrane by molecules too large to fit through proteins.  Relies on ability of membrane to change shape and create vesicles and reseal itself

29. Endocytosis  Take large molecules in  Cell membrane pinches in and surrounds molecule in membrane

30. Phagocytosis  “Cell eating”: engulfing entire cell; done by some white blood cells

33. Receptor-mediated Endocytosis  Allows smaller molecules to enter  Molecules bind to specific receptor proteins  Egg cells take in yolk protein by this method

34. Pinocytosis  “Cell drinking”; cells take in fluid and the solutes it contains

35. Exocytosis  Expelling large molecules; reverse of endocytosis

38. Cells transport substances across their membranes. Choose ONE of the following four types of cellular transport.  Osmosis  Active Transport  Facilitated Diffusion  Endocytosis/exocytosis  For the transport type you choose,  Describe the transport process and explain how the organization of cell membranes functions in the movement of specific molecules across membranes