1. Membrane structure and function

2. Phospholipids Membranes are made of fat (lipids)

3. Hydrophilic head Hydrophobic tails

4. Hydrophilic head Hydrophobic tail WATER Bilayer

6. Biological membranes are fluid mosaics of lipids and proteins

7. Hydrophilic region of protein Hydrophobic region of protein Phospholipid bilayer Fluid Mosaic Model of Singer and Nicolson (1972)

8. Freeze fracture (electron microscopy) Evidence for fluid mosaic model

9. Knife Cytoplasmic layer Extracellular layer Cytoplasmic layer Plasma membrane Extracellular layer Proteins

10. Lateral movement (~10 7 times per second) Flip-flop (~ once per month) Movement of phospholipids Membrane fluidity

11. Viscous Fluid Unsaturated hydrocarbon tails with kinks Membrane fluidity Saturated hydro- carbon tails

12. Cholesterol Cholesterol within the animal cell membrane

13. Fibers of extracellular matrix (ECM) Glycoprotein Carbohydrate Microfilaments of cytoskeleton Cholesterol Integral protein Peripheral proteins CYTOPLASMIC SIDE OF MEMBRANE EXTRACELLULAR SIDE OF MEMBRANE Glycolipid Membrane Proteins

14. Fibers of extracellular matrix (ECM) Glycoprotein Carbohydrate Microfilaments of cytoskeleton Cholesterol Integral protein Peripheral proteins CYTOPLASMIC SIDE OF MEMBRANE EXTRACELLULAR SIDE OF MEMBRANE Glycolipid Membrane Proteins

15. EXTRACELLULAR SIDE N-terminus C-terminus CYTOPLASMIC SIDE  Helix Transmembrane protein

17. Enzymes Signal Receptor ATP Transport Enzymatic activity Signal transduction Membrane Proteins: functions

18. Glyco- protein Cell-cell recognition Intercellular joining Attachment to the cytoskeleton and extra- cellular matrix (ECM) Membrane Proteins: functions

19. Passive transport Active transport Bulk transport Moving stuff around

20. Diffusion

22. Molecules of dyeMembrane (cross section) WATER Net diffusion Equilibrium Diffusion of one solute Passive Transport

23. Passive transport is the diffusion of a substance across a biological membrane No energy required Passive Transport

24. Lower concentration of solute (sugar) Higher concentration of sugar Same concentration of sugar Selectively permeable mem- brane: sugar mole- cules cannot pass through pores, but water molecules can H2OH2O Osmosis Diffusion of water across a membrane

25. Animal cell Lysed H2OH2O H2OH2O H2OH2O Normal Hypotonic solution Isotonic solutionHypertonic solution H2OH2O Shriveled

26. Getting across the membrane

27. Rather directly

28. Exocytosis

30. Some material can diffuse through membranes on their own Diffusion Passive

31. Some materials diffuse through only with help Diffusion Passive

32. Some materials must be pumped through membranes Against Diffusion Active (not passive)

33. Diffusion Facilitated diffusion Passive transport ATP Active transport