Co-transport of glucose

• How does co-transport work?

  One molecule moves down its gradient to move another against its gradient
• What is an example of co-transport in the body?

  Glucose co-transport in the small intestine
• How are sodium ions involved in glucose co-transport?

  Sodium ions move down their gradient and glucose is moved with them
• How does glucose move into the blood after being co-transported?

  By facilitated diffusion through a protein channel
• How does the rate of respiration affect the rate of active transport?

  A higher rate of respiration produces more ATP for active transport
• What happens to active transport if respiration is inhibited?


  Active transport cannot take place
• Why does co-transport have to be used to move glucose into the epithelial cells in the small intestine?

  Because the concentration of glucose is usually higher in the epithelial cells than in the small intestine so it must go against the concentration gradient.
• Describe the process of the co-transport of glucose and amino acids.

  1. Sodium ions are actively transported out of the epithelial cell into the blood in the capillary.
  2. This reduces the sodium ion concentration of the epithelial cell.
  3. Sodium ions can then diffuse from the lumen down their concentration gradient into the epithelial cell.
  4. The protein the sodium ions diffuse through is a co-transporter protein, so either glucose or amino acids also attach and are transported into the epithelial cell against their concentration gradient.
  5. Glucose then moves by facilitated diffusion from the epithelial cell to the blood.