The document discusses the structure and function of cell membranes. Cell membranes are made up of a phospholipid bilayer with embedded proteins. The phospholipid bilayer is selectively permeable and allows small molecules like oxygen, carbon dioxide, and water to pass through. Larger molecules and ions require transport proteins to move them across the membrane. Membranes also contain integral proteins that function as enzymes, receptors, and channels to transport molecules across the membrane. Membranes are fluid and the components within them can move laterally through the bilayer.

1. Chapter 7 Membrane Structure and Function

2. Figure 7-01

4. LE 7-3 Hydrophilic region of protein Hydrophobic region of protein Phospholipid bilayer

5. LE 7-2 Hydrophilic head Hydrophobic tail WATER WATER

6. LE 7-5 Lateral movement (~10 7 times per second) Flip-flop (~ once per month) Viscous Movement of phospholipids Fluid Unsaturated hydrocarbon tails with kinks Membrane fluidity Saturated hydro- carbon tails Cholesterol Cholesterol within the animal cell membrane

7. LE 7-7 Fibers of extracellular matrix (ECM) Glycoprotein Carbohydrate Microfilaments of cytoskeleton Cholesterol Integral protein Peripheral proteins CYTOPLASMIC SIDE OF MEMBRANE EXTRACELLULAR SIDE OF MEMBRANE Glycolipid

8. LE 7-9a Enzymes Signal Receptor ATP Transport Enzymatic activity Signal transduction

9. LE 7-9b Glyco- protein Cell-cell recognition Intercellular joining Attachment to the cytoskeleton and extra- cellular matrix (ECM)

10. LE 7-8 EXTRACELLULAR SIDE N-terminus C-terminus CYTOPLASMIC SIDE  Helix

11. LE 7-10 Plasma membrane: Cytoplasmic face Extracellular face Transmembrane glycoprotein Plasma membrane: Secreted protein Vesicle Golgi apparatus Glycolipid Secretory protein Transmembrane glycoproteins ER

12. LE 7-7 Fibers of extracellular matrix (ECM) Glycoprotein Carbohydrate Microfilaments of cytoskeleton Cholesterol Integral protein Peripheral proteins CYTOPLASMIC SIDE OF MEMBRANE EXTRACELLULAR SIDE OF MEMBRANE Glycolipid Activity: Selectively Permeable Membranes

14. LE 7-11a Molecules of dye Membrane (cross section) WATER Net diffusion Net diffusion Equilibrium Diffusion of one solute

15. LE 7-11b Net diffusion Net diffusion Equilibrium Diffusion of two solutes Net diffusion Net diffusion Equilibrium Activity: Diffusion

16. LE 7-12 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 H 2 O Osmosis Activity: Osmosis

20. LE 7-13 Animal cell Lysed H 2 O H 2 O H 2 O Normal Hypotonic solution Isotonic solution Hypertonic solution H 2 O Shriveled H 2 O H 2 O H 2 O H 2 O Plant cell Turgid (normal) Flaccid Plasmolyzed Activity: Osmosis

21. LE 7-14 Filling vacuole 50 µm 50 µm Contracting vacuole

22. LE 7-15a EXTRACELLULAR FLUID Channel protein Solute CYTOPLASM

23. LE 7-15b Carrier protein Solute Activity: Facilitated Diffusion

24. LE 7-17 Diffusion Facilitated diffusion Passive transport ATP Active transport

25. LE 7-16 Cytoplasmic Na + bonds to the sodium-potassium pump CYTOPLASM Na + [Na + ] low [K + ] high Na + Na + EXTRACELLULAR FLUID [Na + ] high [K + ] low Na + Na + Na + ATP ADP P Na + binding stimulates phosphorylation by ATP. Na + Na + Na + K + Phosphorylation causes the protein to change its conformation, expelling Na + to the outside. P Extracellular K + binds to the protein, triggering release of the phosphate group. P P Loss of the phosphate restores the protein’s original conformation. K + is released and Na + sites are receptive again; the cycle repeats. K + K + K + K + K + Activity: Active transport

27. LE 7-18 H + ATP CYTOPLASM EXTRACELLULAR FLUID Proton pump H + H + H + H + H + + + + + + – – – – –

28. LE 7-19 H + ATP Proton pump Sucrose-H + cotransporter Diffusion of H + Sucrose H + H + H + H + H + H + + + + + + + – – – – – –

29. Activity: Exocytosis & Endocytosis

30. LE 7-20a CYTOPLASM Pseudopodium “ Food” or other particle EXTRACELLULAR FLUID Bacterium Food vacuole An amoeba engulfing a bacterium via phagocytosis (TEM) Pseudopodium of amoeba 1 µm Food vacuole PHAGOCYTOSIS

31. LE 7-20b Plasma membrane Pinocytosis vesicles forming (arrows) in a cell lining a small blood vessel (TEM). 0.5 µm Vesicle PINOCYTOSIS

32. LE 7-20c Receptor RECEPTOR-MEDIATED ENDOCYTOSIS Ligand Coated pit Coated vesicle Coat protein Coat protein Plasma membrane 0.25 µm A coated pit and a coated vesicle formed during receptor- mediated endocytosis (TEMs).