Facilitated diffusion

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  • Created by: aarafa11
  • Created on: 19-11-17 18:52

Why we need it?

  • Plasma membrane is not readily permeable to molecules
    • charged ions and polar molecule don't diffuse 
      • due to a hydrophobic tail 
    • ONLY SMALL, NON-POLAR MOLECULES
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How does it work

  • By  transmembrane channel /carrier (CARRIER PROTEIN AND PROTEIN CHANNELS)
    • Carrier protein 
      • molecules (O2) that are specific to the protein will bind to it
      • it'll change the shape of the protein 
      • the molecule will be released inside the membrane
      • no external energy
    • Protein channel
      • water filled hydrophilic channels which are specific 
      • allow specific water-soluble ions
      • control over entry and exit of ions
  • Passive process
    • inbuilt kinetic energy (NO ATP) 
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Role in diffusion

  • Theres a high concetration of amino acid and glucose
    • within the ileum
    • than the blood
  • Therefore, a concentration gradient
  • Glucose moves down by FACILIATED DIFFUSION
    • into blood
  • The glucose is continueously being removed by cells during RESPIRATION
    • Blood is circulated by the heart
    • This MAINTAINS a concentration gradient
  • Therefore, the rate of movement by diffusion is INCREASED
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