Cel Membrane Structure and Function

1. Cell Membranes

3. Phospholipid Review Glycerol Change from Triglyceride to Phospholipid Fatty Acid Fatty Acid Glycerol Polar group Fatty Acid Fatty Acid Fatty Acid

4. Fluid Mosaic Model of Membrane Structure Oligosaccharides Cytoplasm Membrane Proteins Cholesterol Outer Surface

14. Diffusion of Dye in Water Time 0 Steep Concentration Gradient Time 1 Reduced Concentration Gradient Dispersing Time 2 No Concentration Gradient Random Dispersal

15. Simple Diffusion (extracellular fluid) (cytoplasm) Some molecules diffuse freely across

16. Facilitated Diffusion: Carriers Carrier protein has binding site for molecule Molecule enters binding site Carrier protein changes shape, transporting molecule across membrane Carrier protein resumes original shape (Inside Cell) (Outside Cell) Diffusion Channel Protein Diffusion Gradient Molecule in Transit

19. Osmosis I “ Bound” water molecules clustered around sugar: cannot fit through pore “ Free” water molecule: can fit through pore

20. The Effects of Osmosis Isotonic Solution Equal movement of water into and out of cells Net movement of water out of cells Net movement of water into cells Hypertonic Solution Hypotonic Solution Normal RBCs Shriveled RBCs Swollen RBCs

22. Active Transport Steps Inside Cell Outside Cell Energy Provider Spent Energy Provider Transported Molecule 1 2 3 4

24. Endocytosis (extracellular fluid) Pinocytosis vesicle containing extracellular fluid) (cytoplasm) 1 2 3 cell (extracellular fluid) (cytoplasm) 1 2 3 4 coated pit forming Receptor-mediated Endocytosis Phagocytosis coated vesicle nutrients receptors food particle pseudopod particle enclosed in food vacuole

25. Receptor- mediated Endocytosis I Begins with a shallow pit in plasma membrane Pit is coated with protein (cytoplasm) (extracellular fluid) coated pit protein coating extracellular particles bound to receptors plasma membrane Pit deepens a b 0.1 Micrometer

26. Receptor- mediated Endocytosis II Pit deepens further and begins to pinch off Eventually becomes a coated vesicle c d 0.1 Micrometer coated vesicle

27. Exocytosis (cytoplasm) 1 Vesicle (extracellular fluid) plasma membrane 2 Secreted Material 3

29. Surface to Volume Ratio 3 1 3 S/V Ratio 113.1 113.1 4.2 Volume 4/3  r 3 339.4 113.1 12.6 Surface 4  r 2 1.0 3.0 1.0 Radius Grow Break apart

30. Cell Communication Structures Desmosome desmosome Protein strands holding cells together Protein filaments in cytoplasm Small intestine Plasma membrane (edge view) Cells lining small intestine Tight Junction Tight junctions formed by strands of protein Plasma membrane (edge view) Cells lining bladder Tight junctions seal membranes of adjacent cells together

31. Cell Attachment Structures Gap Junctions desmosome Gap Junctions: pairs of channels connect insides of adjacent cells Liver Plasma membrane (edge view) Liver cells Plasmodesmata Plasmodesmata connect insides of adjacent cells Plasma membrane (edge view) Root cells Cell wall (edge view) Middle lamella (edge view) Root

32. The End