co-transport

• Co transport


  The transport of one substance is coupled with the transport of another across a membrane
• Glucose transport in small intestine

  1. Glucose transported from the lumen of intestine into epithelial cells lining intestine

  2. Facilitated by co-transport of sodium ions

  3. Sodium ions actively transported out of cell by sodium-potassium pump, creating ion gradient

  4. Sodium ions re-enter cell, bringing glucose molecules along against their concentration gradient
• Epithelial cells in small intestine

  • Contain lots of mitochondria to provide ATP for sodium-potassium pump
  • Membrane folded into many microvilli to increase surface area and provide more space for membrane proteins
• Sodium-potassium pump


  Actively transports sodium out of cell and potassium into cell, using ATP to power the co-transport by creating an ion gradient
• Substances transported by co-transport

  • Glucose
  • Amino acids
• Co-transport is driven by the concentration gradient of sodium ions created by the sodium-potassium pump