Membranes and membrane transport

97,826 views

Published on

For the IB Biology Cells unit.

Published in: Education, Technology, Business
0 Comments
22 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
97,826
On SlideShare
0
From Embeds
0
Number of Embeds
74,361
Actions
Shares
0
Downloads
2,917
Comments
0
Likes
22
Embeds 0
No embeds

No notes for slide

Membranes and membrane transport

  1. 1. Membranes Stephen Taylor i-Biology.net Photo credit: Plasmolysis by MNolf via http://commons.wikimedia.org/wiki/File:Rhoeo_Discolor_-_Plasmolysis.jpg
  2. 2. Pre-assessment • What can you label on this diagram? • Can you explain three different methods of transport across a membrane?
  3. 3. Plasma Membrane • • Label the diagram with components & functions Identify components that are involved in transport.
  4. 4. Stephen Taylor http://sciencevideos.wordpress.com
  5. 5. Stephen Taylor http://sciencevideos.wordpress.com
  6. 6. Stephen Taylor http://sciencevideos.wordpress.com
  7. 7. Stephen Taylor http://sciencevideos.wordpress.com
  8. 8. Stephen Taylor http://sciencevideos.wordpress.com
  9. 9. Stephen Taylor http://sciencevideos.wordpress.com
  10. 10. Stephen Taylor http://sciencevideos.wordpress.com
  11. 11. Stephen Taylor http://sciencevideos.wordpress.com
  12. 12. Stephen Taylor http://sciencevideos.wordpress.com
  13. 13. Stephen Taylor http://sciencevideos.wordpress.com
  14. 14. Stephen Taylor http://sciencevideos.wordpress.com
  15. 15. Stephen Taylor http://sciencevideos.wordpress.com
  16. 16. Stephen Taylor http://sciencevideos.wordpress.com
  17. 17. Stephen Taylor http://sciencevideos.wordpress.com
  18. 18. Plasmolysis in Elodea and in onion cells. 1. Set up slides of Elodea cells and onion cells, with tap water medium. 2. Find cells under the microscope. Draw and label what you see. Include magnification. You might need to try different stains. 3. Draw salt solution through the slides. Observe and draw the effects. 4. Explain the effects of changing the salt concentration on the cells.
  19. 19. Stephen Taylor http://sciencevideos.wordpress.com
  20. 20. Stephen Taylor http://sciencevideos.wordpress.com
  21. 21. Explain passive transport across membranes by simple diffusion & facilitated diffusion. Simple & facilitated diffusion are passive. • No energy input is required There is a net movement of molecules from one side of the membrane to the other. • • The motion of molecules is random (Brownian motion) But there is an overall general movement in one direction. This net movement is down the concentration gradient. • From areas of high concentration to low concentration. Movement is across a selectively or partially permeable membrane Dependent on size or properties, some molecules can cross and not others. Simple Diffusion Occurs when the molecule’s properties allow them pass across the membrane. The rate of diffusion is affected by: • magnitude of concentration gradient • SA:Vol ratio (more membranes, more transport per unit volume) • Length of diffusion pathway (longer journey gives slower diffusion). Facilitated Diffusion Some molecules cannot cross easily, for example if they are polar the phospholipids of the bilayer will repel them. Channel proteins are integral membrane proteins that pass through the membrane. Their properties allow molecules to pass through (e.g. polar molecules or ions). Activation of these channels might be voltagegated (e.g. in neurons) or binding-activated.
  22. 22. Stephen Taylor http://sciencevideos.wordpress.com
  23. 23. Stephen Taylor http://sciencevideos.wordpress.com
  24. 24. Stephen Taylor http://sciencevideos.wordpress.com
  25. 25. Stephen Taylor http://sciencevideos.wordpress.com
  26. 26. Stephen Taylor http://sciencevideos.wordpress.com
  27. 27. Stephen Taylor http://sciencevideos.wordpress.com
  28. 28. Stephen Taylor http://sciencevideos.wordpress.com
  29. 29. Stephen Taylor http://sciencevideos.wordpress.com
  30. 30. Stephen Taylor http://sciencevideos.wordpress.com
  31. 31. Stephen Taylor http://sciencevideos.wordpress.com
  32. 32. Stephen Taylor http://sciencevideos.wordpress.com
  33. 33. Stephen Taylor http://sciencevideos.wordpress.com
  34. 34. Stephen Taylor http://sciencevideos.wordpress.com
  35. 35. Stephen Taylor http://sciencevideos.wordpress.com
  36. 36. Active transport uses energy, in the form of ATP, to move molecules across a selectively permeable membrane against the concentration gradient, using protein pumps. Why do this? To move molecules against the concentration gradient or to create a large concentration gradient across a membrane. Protein pumps These are integral, passing through the membrane. They are specific – only working with the target molecule. What happens? 1. Target molecules bind to the pump. 2. ATP also binds to the pump. ATP is broken, releasing energy and causing a conformational (shape) change in the protein pump. 3. This conformational change pushes the molecules across the membrane. 4. The molecule unbinds, and the pump reverts back to the original shape. Examples • • Sodium-potassium pump is used to re-polarise neurons after an action potential, ready to fire again. Proton pumps in mitochondria generate a high concentration gradient of H+ ions, ready for chemiosmosis through ATP synthase, used for generating ATP.
  37. 37. Active transport uses energy, in the form of ATP, to move molecules across a selectively permeable membrane against the concentration gradient, using protein pumps. Why do this? Protein pumps What happens? Examples
  38. 38. Stephen Taylor http://sciencevideos.wordpress.com
  39. 39. Stephen Taylor http://sciencevideos.wordpress.com
  40. 40. Stephen Taylor http://sciencevideos.wordpress.com
  41. 41. Stephen Taylor http://sciencevideos.wordpress.com
  42. 42. Annotate this diagram to explain vesicle transport & exocytosis. Animated tutorial: http://bcs.whfreeman.com/thelifewire8e/content/cat_040/0504003.html
  43. 43. Stephen Taylor http://sciencevideos.wordpress.com
  44. 44. Stephen Taylor http://sciencevideos.wordpress.com
  45. 45. Stephen Taylor http://sciencevideos.wordpress.com
  46. 46. Stephen Taylor http://sciencevideos.wordpress.com
  47. 47. For more resources & links. Please consider a donation to charity via Biology4Good. Click here for more information about Biology4Good charity donations. This is a Creative Commons presentation. It may be linked and embedded but not sold or re-hosted.

×