The Plasma Membrane

1. The Plasma Membrane Essential Questions: How does the structure of the plasma membrane allow it to function as a regulatory organelle and protective barrier for a cell?

3. Plasma Membrane • Function: Maintains homeostasis by controlling substances entering & leaving the cell.

4. Think-pair-shareWhat kinds of substances might need to enter or leave the cell?

5. A cell must take in and keep needed materials, such as glucose, while maintaining a balance with its surroundings.

6. A cell must remove wastes and keep harmful substances from entering.

7. Selective Permeability inside cell • The property of a membrane that allows some materials to pass through while keeping others out. outside cell

8. Selective permeability allows different cells to carry on different activities within the same organism.

9. Structure of the Plasma Membrane

10. outside cell cytoplasm

11. Cholesterol • Stabilizes the membrane by preventing phospholipids from sticking together

12. Proteins • Transport-help move large molecules across the membrane • Markers-helps chemicals recognize certain cells • Enzymes

13. Proteins Transport Proteins Marker Proteins Enzymatic Proteins

14. Channel protein Provide a “tunnel” or channel for molecules to pass through the membrane

15. Carrier protein Protein that picks up a molecule and “carries” it across the membrane

16. Cell recognition protein Carbohydrate chain at the end of a protein and is used for cell to cell recognition and attachment

17. Phospholipids • Phosphate head (glycerol +phosphate) • 2 Fatty acid tails

18. Phospholipids Phosphate “attracted to water” • Phosphate head • polar • hydrophilic “water-loving” • Fatty acid tails • nonpolar • hydrophobic “water-fearing” Fatty acid “repelled by water”

19. Polar Heads Non-polar tails Polar Heads Phospholipids are arranged in a bilayer outside cell inside cell

20. Think - Pair - Share Section 2 Check Phospholipid molecule Why do the phosphate heads point outward and the fatty acid tails point inward? Polar head (includes phosphate group) Nonpolar tails (fatty acids)

21. phospholipids move around • The phospholipids can move sideways through their layer, but not from one layer to the other.

22. Name given to this model of the plasma membrane. Fluidbecause the phospholipids are free to move within the membrane. Mosaic because of the pattern it produces when viewed from above.

23. Talk to a Partner • Plasma Membrane Carbohydrates, transport proteins, cholesterol, phospholipids, bilayer, cytoplasm, outside cell

24. QUESTIONS???

25. What does it mean that a cell membrane has a lipid bilayer?

26. What is the function of this structure?

27. What is the function of this structure?

28. What is the function of this structure?

29. Describe the 2 components of this structure

30. Section 2 Check Which of the following best describes the plasma membrane's mechanism in maintaining homeostasis? A. protein synthesis B. selective permeability C. fluid composition D. structural protein attachment

31. Explain why the model of the plasma membrane is called the fluid mosaic model. Section 2 Check

32. Cornell SummarY