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Membrane

Membrane. Function. Passive Transport. Concentration Gradient A difference in concentrations across the plasma membrane. Simple Diffusion. Particles diffuse through phospholipid bilayer. Facilitated Diffusion. Translocating (Carrier) Proteins Bind particle Change shape

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Membrane

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  1. Membrane Function

  2. Passive Transport • Concentration Gradient • A difference in concentrations across the plasma membrane

  3. Simple Diffusion • Particles diffuse through phospholipid bilayer

  4. Facilitated Diffusion • Translocating (Carrier) Proteins • Bind particle • Change shape • Force through membrane

  5. Facilitated Diffusion • Channel Proteins • Passage through proteins • Gated - open in response to stimulus • Membrane proteins exhibit… • Specificity • Saturation • Inhibition

  6. Osmosis • Diffusion and fac. diffusion of water

  7. Osmosis • Continues until equilibrium reached • OR until another force resists osmosis Yp = Pressure Potential Ys= Solute Potential

  8. Osmosis • Water Potential (Y) • Water moves from high Y to low Y. • Depends on Ys and Y p • Ys = - i C R T Temperature (in K; 273 + C) Pressure Constant (0.083) Ionization constant (units/molecule) Molar Conc. 0 -24.3 -9.7

  9. Active Transport • Membrane proteins use ATP to increase conc gradient

  10. Active Transport • Sodium-Potassium Pump

  11. Electrochemical Gradient • Difference in charges and concentrations across a membrane • Produced by electrogenic pumps • Serves as potential energy that can be tapped later

  12. Exocytosis & Endocytosis

  13. Transport Review • What types of particles have the toughest time getting through a phospholipid bilayer? • What similarities exist between transport proteins and enzymes? • What’s the difference between carrier proteins and channel proteins? • A certain membrane is impermeable to ions and can withstand 2 bars of pressure before rupture. At 27oC, how high can the salt concentration be inside the cell before rupturing in a distilled water environment?

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