Honors Biology Chapter 7Section 3 Cell Boundaries

1. Honors Biology Chapter 7Section 3 Cell Boundaries SC B- 2.5: Explain how active, passive, and facilitated transport serve to maintain the homeostasis of the cell.

2. Cell Membrane • surround all cells • is a thin, flexible barrier that acts like the cell’s “gate keeper” • made of lipid-bilayer • provides protection & support

3. Cell Membrane: Lipid-Bilayer • Fluid Mosaic Model • phospholipids

4. Plasma MembraneFluid Mosaic Model • resembles an ever-moving sea of fluid lipids that has large proteins bobbing along throughout the lipids

5. Membrane Lipids • Phospholipids (~70% of membrane) • Cholesterol: • changes fluidity of membrane • Glycolipids • sugar molecule on lipid

6. Membrane Proteins • Integral Proteins • go all the way thru the membrane • channel proteins • receptor proteins • Peripheral Proteins • on inside or outside of membrane • +/- attached to integral proteins

7. Cell Membrane

8. Cell Walls • found in: • plant cells • fungi cells • algae • bacteria • secreted by cell membrane • allow O2, CO2, glucose, & H2O to pass through

9. Cell Wall

10. Cell Wall

11. Diffusion Thru Cell Boundaries • all cells bathed in liquid • solutes dissolve in solvent (water) • concentration: • mass of the solute /vol of solution

12. Passive Transport • does not require cell to spend energy to move substances • substances moving from area where it is in higher concentration  area where it is in lower concentration

13. Types of Passive Transport • simple diffusion • osmosis • facilitated diffusion

14. Diffusion • all particles have KE • due to the KE of particles they will move about until they are evenly distributed in the space they occupy • what we see is particles moving from where they are in high concentration  where they are in lower concentration

15. Diffusion • a form of passive transport • cell not spending nrg to make it happen • movement of particles continues even after equilibrium reached

16. Equilibrium • when concentration of solutes equal thru out a system • since solute particles still moving it is also referred to as dynamic equilibrium

17. Diffusion • http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html

18. Osmosis • is the diffusion of water across a semi-permeable membrane • it‘s water moving from where water is in high concentration  water is in lower concentration • semi-permeable = selectively permeable

19. Osmosis • Predict what will happen in the container on other side

20. Osmosis • water will move down its concentration gradient until equilibrium is reached • when concentrations of solutes same on both sides of membranes : equilibrium reached

21. Osmosis

22. Isotonic Solutions • cells are in isotonic solutions when the concentration of solutes inside cell = concentration of solutes outside cell • for human cells isotonic soultions = 0.9% NaCl

23. RBCs in Isotonic Solutions

24. Hypertonic Solutions • “above strength” • cells in ECF (extracellular fluid) with a higher concentration of solutes than inside cell • water in higher concentration inside cell so water leaves cell by osmosis…..cell shrinks….called crenation

25. RBCs in Hypertonic Solution

26. Crenation in Cells with Cell Walls • called plasmolysis

27. Hypotonic Solutions • “below strength” • water now in higher concentration in ECF so water will move from outside cell  inside cell…. cell swells and eventually pops….. called hemolysisif it is a RBC, other cells it is called: cytolysis

28. HemolysisofRBCs

29. Cells with Cell Walls in Hypotonic Solutions

30. In Review:

31. Facilitated Diffusion • some substances move in/out of cells by diffusion but require a transport protein to cross the cell membrane • substance still moving from side with higher concentration  side with lower concentration • example: sugars move into cells by facilitated diffusion

32. Facilitated Diffusion

33. Facilitated Diffusion • http://programs.northlandcollege.edu/biology/Biology1111/animations/passive3.swf

34. Active Transport • moving substances in/out of cell that requires cells to spend energy (usually in form of ATP) • substances are moving against their concentration gradients (from where they are in low concentration  high concentration)

35. Types of Active Transport • Pumps • Endocytosis • Exocytosis

36. Pumps • protein in cell membrane that “pumps” ion or molecule in/out of cell against its concentration gradient • most pumps use ATP as source of energy • most important pump is Na+/K+/ATPase pump

37. Na+/K+/ATPase Pump

38. Na+/K+/ATPasePump • http://www.brookscole.com/chemistry_d/templates/student_resources/shared_resources/animations/ion_pump/ionpump.html

39. Endocytosis • process of cell taking up material into cell by means of infolding pockets of cell membrane

40. Phagocytosis • cell “eating” • done by unicellular organisms and phagocytes in multicellular organisms • macrophages

41. Phagocytosis

42. Pinocytosis • cell “drinking” • cells take up liquid from surroundings

43. Pinocytosis

44. Exocytosis • when cells need to expel larger amounts of materials than can be expelled thru transport protein • storage vacuole moves to cell membrane; its membrane fuses with cell membrane expelling contents into ECF

45. Exocytosis

46. Exocytosis

47. Endocytosis & Exocytosis • endocytosis is removing some membrane from cell membrane • exocytosis is adding some membrane to cell membrane • usually evens out