Biology ~ 1.4: Membrane Transport

Biology ~ 1.4: Membrane Transport

1. Fluid Mosaic Model

2. Movement

   • Simple Diffusion
     • Passive
     • High concentration to low
       • Down concentration gradient
   • Osmosis
     • Down Ψ gradient
       • Strong solution = lots of solute = low Ψ
     • Across selectively permeable membrane
     • WATER ONLY
     • Hypertonic
       • Lower concentration of water OUTSIDE cell
         • Water diffuses out of cell
     • Isotonic
       • Equilibrium
     • Hypotonic
       • Lower concentration of water INSIDE cell
         • Water diffuses into cell
     • Passive
     • Water displacement
   • Facilitated Diffusion
     • Passive
     • From high to low concentration
     • Help from carrier proteins
     • ENERGY NOT REQUIRED
     • Molecules too big to diffuse normally so they require help
       • Eg: Glucose
   • Active Transport
     • Against concentration gradient
     • Requires energy
       • ATP
         • ADP
         • Pi

3. Rate of diffusion

   • Surface Area
     • Increase
       • Faster
   • Concentration
     • Increase
       • Faster
   • Diffusion Path
     • Increase
       • Slower
   • Membrane Proteins
     • Increase
       • Faster

4. Fluidity

   • Endocytosis
     • Movement of material into the cytoplasm
   • Exocytosis
     • Movement of material out of the cytoplasm
   • Phagocytosis
     • Solid molecules
   • Pinocytosis
     • Liquid molecules

5. Transport

   • Uniport
     • One way
   • Cotransport
     • Symport
       • Two ways (same direction)
     • Antiport
       • Two ways (opposite direction)

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