Types of Transport

Types of Transport

1. Active Transport

   • Requires ATP from mitochondria
     • Energy from respiration
   • Goes against the concentration gradient
   • Uses carrier proteins
   • E.g. sodium potassium pump, absorption by plants, digestion

2. Facilitated Diffusion

   • Moves with the concentration gradient (high to low)
   • Passive
   • Needs channel proteins or carrier proteins
     • Carrier proteins - large molecules
       • The large molecule binds to a protein, which changes shape
         • This is released on the other side of the proteins
     • Channel proteins - charged molecules
       • The proteins form pores in the membrane for charged particles to travel through
         • Proteins are specific to certain particles

3. Diffusion

   • Moves with the concentration gradient
   • Only non-polar and small polar
     • Particles with big charges will be attracted to oppositely charged ions
   • E.g. oxygen and carbon dioxide
   • Passive - No energy required

4. Osmosis

   • Movement of water from an area of high water potential to one of low water potential
   • Over a partially permeable membrane

5. Co-Transport

   • Two molecules transported at once
   • In the ileum of the small intestine
     • Na+ ions are actively transported out of epithelial cells in the ileum into the blood
       • Via a sodium - potassium pump
     • Sodium then diffuses out of the lumen of the small intestines into the epithelial cell of the lumen
       • Transported via a sodium - glucose co-transporter protein
         • Concentration of glucose in the ileum's epithelial cell increases
     • Glucose then leaves the epithelial cell through the blood via facilitated diffusion, using channel proteins