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Transport

Transport. Across Biological Membranes. Review for Transport. What are the two parts of a solution? In cells, what is normally the solvent? How would you describe the activity of solute particles in solutions?. Passive Transport. Concentration Gradient

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Transport

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  1. Transport Across Biological Membranes

  2. Review for Transport • What are the two parts of a solution? • In cells, what is normally the solvent? • How would you describe the activity of solute particles in solutions?

  3. Passive Transport • Concentration Gradient • A difference in concentrations across a membrane

  4. Simple Diffusion Mainly small, nonpolar • Particles diffuse through lipid bi-layers to reach equilibrium

  5. Facilitated Diffusion • Membrane proteins carry materials through the lipid bilayer. • Particle binds to membrane protein. • Membrane protein changes shape. • Particle is released on the other side.

  6. Channel Proteins • Membrane protein opens a passage for materials through the lipid bilayer.

  7. HYPOTONIC HYPERTONIC H2O H2O H2O H2O H2O H2O HYPERTONIC HYPOTONIC H2O H2O H2O H2O H2O H2O H2O H2O H2O H2O Osmosis • Diffusion of water • When solute cannot cross membranes to reach equilibrium, the solvent (water) does • Water moves from where it is purest (hi conc.) to where it is least pure (lo conc.)

  8. Transport Review • What two things are always true of passive transport? • What are the examples of passive transport we discussed? • Why shouldn’t we drink salt water? • How do we regulate the amount of water (and concentration of solutes) in our bodies?

  9. HI LO HI LO LO HI No E req'd E req'd

  10. Pump • Similar to facilitated diffusion except it’s AT ADP + P ATP

  11. Active Transport • Exocytosis • Pre-packaged materials are released from the cell.

  12. Active Transport • Endocytosis • Cells engulf large materials (nutrients, enemies) with cell membrane.

  13. Active Transport • Endocytosis • Cells engulf large materials (nutrients, enemies) with cell membrane.

  14. Review Questions • What’s the difference between active and passive transport? • In what direction will particles always diffuse? • What happens to a wall-less cell in a hypotonic solution? • Why might a cell want to build up a concentration gradient?

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