Cell (Plasma) Membrane

1. Cell (Plasma) Membrane What is it made of? Why is this a good material for a cell membrane?

2. Cell Membrane • Phospholipid bilayer • Hydrophilic head • Hydrophobic tail

3. Cell Membrane • Homeostasis • Steady state maintained by the body • Selectively Permeable • Regulates what can come in and out of the cell

4. Selectively Permeable (6.3) Breathing CAN Small Nonpolar • (O2) • (CO2) • WATER CANNOT • Large (glucose) • Polar ( exception is water because its so small) • Ion (charged)

5. Proteins in the Cell Membrane • “Fluid Mosaic Model” • Many proteins will help transport molecules across the membrane • Proteins drift freely

6. Membrane Proteins Embedded • Transport Proteins • Cell Recognition Proteins- sugars hang off proteins • Receptors Proteins- receive signals • Enzymes- proteins that make reactions happen

7. Cell Recognition Proteins • Sugars hang off of proteins in the cell membrane • Give us different blood types

9. Receptor Protein Receptor Protein-is a cell membrane protein that receives a signal

10. Transport

11. Passive Transport: Diffusion • Diffusion • The movement of particles HIGH concentration to LOW concentration Why? • Molecules are always in random motion Ex. Perfume, food coloring, tea bag

13. Equilibrium- particles equally spread out

14. Osmosis Water ONLY! • Diffusion of water from HIGH to LOW concentration Solute: Substance in solution that is dissolved (ex. Sugar or Salt) Solvent: Substance in solution that does the dissolving ( ex. Water)

15. TONICITY Hypotonic Environment Hypertonic Environment Isotonic Environment

16. 97% H20 97% H2O 97% H2O Isotonic Same Inside and outside Even, same concentration overall “dynamic equilibrium”“homeostasis contact lens solution, Gatorade

17. Hypotonic 92 % H20 97% H2O Outside Inside Burst, get bigger; firm “cytolysis”- to burst; “turgid”- get firm; “turgor pressure” :pressure inside plant cells to help stand upright - Distilled water ( 100% Water) - Plants standing upright

19. Hypertonic 97% H20 80% Water Inside Outside Smaller, shrink, go limp “plasmolysis”- to wilt, shrivel, loss of pressure; “flaccid”- go limp

20. Hypertonic Red Blood Cells

21. Check Yourself Is the lettuce in a hypertonic isotonic hypotonic environment and why?? Poll

22. Passive Transport: Facilitated Diffusion Facilitated Diffusion • diffusion across a membrane through transport proteins Ex. sugars, ions , alcohol NO ENERGY: From HIGH to LOW concentration

23. Active Transport • Movement of molecules across a membrane require energy • From LOW to HIGH concentrations! • Why? • To maintain a certain internal environment: • 1. Sodium Potassium Pump

24. Active Transport • Exocytosis & Endocytosis • 1. Exocytosis • Removal of materials • Vesicle fuses with membrane, forcing contents out

25. Active Transport • 2. Endocytosis • process of taking in materials by infolding of the cell membrane • Pocket breaks and forms a vesicle in the cell • Ex. • Pinocytosis: take in fluid • Phagocytosis: Large particle/food • Amoeba

28. Concentration Gradient measurement of how the concentration of something changes from one place to another B. Passive Transport: molecules go DOWN concentration gradient from HIGH to LOW concentration C. Active Transport: molecule go UP concentration gradient from LOW to HIGHconcentration

29. Review Video of Transport

30. Elodea Plasmolysis

31. http://www.youtube.com/watch?v=2Th0PuORsWY

32. “Egg”citing “Eggs”perimentCell membrane

33. Egg Lab: Osmosis

36. Why does a plant like hypotonic but an animal does not? • http://www.phschool.com/science/biology_place/labbench/lab1/watpot.html