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INTRODUCTION TO THE CELL MEMBRANE

INTRODUCTION TO THE CELL MEMBRANE. THE PURPOSE OF THE C.M. The CM is essential in making the cell a distinctive unit However, it serves other functions – including: Forming a barrier to prevent unwanted materials from entering the cell

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INTRODUCTION TO THE CELL MEMBRANE

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  1. INTRODUCTION TO THE CELL MEMBRANE

  2. THE PURPOSE OF THE C.M. • The CM is essential in making the cell a distinctive unit • However, it serves other functions – including: • Forming a barrier to prevent unwanted materials from entering the cell • Acting as a gateway allowing materials to enter and exit the cell

  3. SEMI-PERMEABLE MEMBRANE • Though a cell has to be separated from its external environment, it must also be able to bring materials in and out of the cell

  4. Water loving and water hating • In order to be separated from the outside environment, a cell membrane has to be able to create a water-proof barrier

  5. 3D Model

  6. Phospholipid bilayer • CM have two layers: • This allows the membrane to create waterproof layers that prevent water soluble materials from leaking in and out of the cell

  7. Phospholipids • You should recall that a phospholipid is a HYDROPHILIC and HYDROPHOBIC molecule

  8. Phospholipid behaviour • If a bunch of phospholipids were poured into an aqueous environment,

  9. Solubility of Cell Membranes

  10. What else is in there? • In order to move material in and out of the cell, the CM has proteins embedded into it to help it transport material

  11. Phospholipid bilayer (PLB)

  12. Fluid Mosaic Model • Here is where the analogy of the balloon gets tricky

  13. http://www.bio.davidson.edu/people/macampbell/111/memb-swf/membranes.swfhttp://www.bio.davidson.edu/people/macampbell/111/memb-swf/membranes.swf

  14. Protein Receptors • These proteins are designed to “fit” – like a key and lock mechanism – specific molecules that help signal the cell

  15. Protein Receptors

  16. Cell identification • Your cells have identification badges in the form of surface proteins • These proteins are usually only found in the outside layer of the cell

  17. Glycoproteins: Cell identifiers

  18. http://www.theimmunology.com/animations/T%20cells%20Dependent%20Antigens.htmhttp://www.theimmunology.com/animations/T%20cells%20Dependent%20Antigens.htm

  19. Liposomes • Liposomes – essentially a phospholipid bilayer but

  20. Liposomes

  21. Transport through C.M.

  22. Passive Transport • Mediated by channels/pores or transporter proteins

  23. http://highered.mcgraw-hill.com/olc/dl/120068/bio04.swf

  24. Osmosis • Osmosis is the diffusion of water

  25. How can you equalize the concentration of the red particles in the left compartment to the one on the right? How many will move? Will all of them? Move them to the right

  26. How can you make the concentration equal in both compartments if you CAN’T move the red particles this time? This time towards the left – to increase the number of blue particles which decreases the concentration of red particles This time move only the blue – but which way will they move?

  27. Osmosis: The movement of water

  28. Cells in iso-, hyper-, and hypotonic soltuions

  29. http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htmhttp://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm

  30. Active Transport • Active transport uses the energy of ATP to:

  31. http://highered.mcgraw-hill.com/olc/dl/120068/bio03.swf

  32. http://highered.mcgraw-hill.com/olc/dl/120068/bio02.swf

  33. Exocytosis

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