Cell membrane and transport

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Cell membrane and transport

  1. 1. Structure and Function of the Cell Membrane
  2. 2. Cell Membrane • Gatekeeper • Regulates what comes in and out of the cell • Main components: proteins and phospholipids • The cell membrane is selectively permeable • Allows some things through without energy, but not everything
  3. 3. Cell Wall • Found only in plant cells and bacteria cells • Main function is support
  4. 4. Cell membrane parts • phosopholipids • made of two sides: head and tail • the head is hydrophillic (able to interact with water) • the tail is hydrophobic (not able to interact with water)
  5. 5. Cell membrane parts • carrier proteins • allow larger or difficult molecules to get through the membrane • sometimes they require energy to open/close like a door • other times they simply act as a tunnel
  6. 6. Diffusion • The movement of molecules from an area of high concentration to an area of low concentration • Molecules tend to “spread out” • Requires no energy
  7. 7. Equilibrium • When molecules are evenly spread throughout a space
  8. 8. Osmosis • The diffusion of water across a membrane • H2O molecules are able to go in between the phospholipids based on size and a slight electrical charge. • Water will travel to where there is a lower concentration • If you add something like salt to the solution…
  9. 9. Rule for Osmosis: Water will get sucked to wherever there is a higher concentration of salt. The following slides illustrate what direction water travels if a cell is placed in different solutions.
  10. 10. Cells In Different Solutions "ISO" means the same; water stays in equilibrium.
  11. 11. Hypo = less Cell fills with water and may burst, or organelles called “contractile vacuoles” remove excess water
  12. 12. Hyper = more Cell will shrink or die, plant leaves wilt and droop. Why is it dangerous to drink sea water? Why does pouring salt on a slug kill it?
  13. 13. Passive Transport • Requires no energy • Diffusion & Osmosis • Facilitated Diffusion: carrier proteins “help” molecules across the membrane like a tunnel
  14. 14. ACTIVE TRANSPORT • Requires the cell to use energy • Carrier Proteins or Pumps found in the membrane move materials across • Open/close like a door
  15. 15. Endocytosis/Exocytosis • Taking “in” or letting “out” large molecules by the cell • Phagocytosis = “phood”, taking in food particles • Pinocytosis = liquid substances

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