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Ch 5 Homeostasis and cell transport

Ch 5 Homeostasis and cell transport. How do cells get the things they need? How do they get rid of their wastes? How do cells transport stuff?. 5-1 Passive transport. Materials must be able to cross the cell membrane Some don’t require energy input: Passive transport

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Ch 5 Homeostasis and cell transport

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  1. Ch 5Homeostasis and cell transport

  2. How do cells get the things they need? • How do they get rid of their wastes? • How do cells transport stuff?

  3. 5-1 Passive transport • Materials must be able to cross the cell membrane • Some don’t require energy input: Passive transport • Diffusion: movement of particles from area of high to low concentration

  4. Diffusion • Two solutions can have different concentrations of solute (particles) • Concentration gradient: the difference in concentration of molecules • Diffusion driven by kinetic energy • Molecules are in constant motion • Diffusion occurs until equilibrium is reached

  5. Diffusion across membranes • Diffusion across a membrane is called simple diffusion • Not everything can diffuse through a membrane • Limits include • Size • Polarity

  6. Osmosis • Osmosis: process by which water molecules diffuse across a membrane from an area of high to low concentration • Form of passive transport • Direction of movement depends on relative concentration of solutes in solution

  7. Direction of osmosis • If concentration of solutes outside of cell is lower than inside the cell, the solution outside is hypotonic • Water diffuses into cell • Animal cells can lyse (burst) • If concentration of solutes outside the cell is higher than inside, the solution outside is hypertonic • Water diffuses out of cell • Plasmolysis (cell shrinks) • When concentrations are equal: isotonic • Equal movement into and out of the cell

  8. Animal Cells (red blood cells)

  9. Plant cells

  10. More osmosis stuff • Turgor pressure: pressure that water exerts against plant cell wall • Page 99: contractile vacuoles: remove excess water • `http://www.youtube.com/watch?v=9Ynm5ZOW59Q

  11. Facilitated diffusion • Passive diffusion • Molecules cross cell membrane through transport proteins

  12. Active transport • Movement of substances from low to high concentrations • Against the concentration gradient • Requires energy

  13. Types of active diffusion • Endocytosis and Exocytosis • http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter5/endocytosis_and_exocytosis.html - • http://www.youtube.com/watch?v=K7yku3sa4Y8

  14. Types of active diffusion • Endocytosis: fluid, macromolecules, or other large particles brought into cell • Pouch forms in membrane lipids • Materials fill pouch • Pouch pinches in and breaks off from membrane • Now a vesicle • Two types: • Pinocytosis: transport of fluids (“cell drinking”) • Phagocytosis: large particle transport (“cell eating”) • http://www.youtube.com/watch?v=pvOz4V699gk&feature=fvwrel

  15. Exocytosis • Process by which a substance is released by a cell • http://www.youtube.com/watch?v=U9pvm_4-bHg

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