Co-transport

Question 1

What is co-transport?

Answer 1

A process that moves two substances across a cell membrane at the same time, involving a carrier protein

Question 2

What are the 3 proteins involved in co-transport of glucose?

Answer 2

• Sodium potassium pumps
• Sodium-glucose co-transporter proteins
• Glucose protein channels

Question 3

What is the role of sodium potassium pumps?

Answer 3

They actively transport sodium ions out of the epithelial cells and potassium ions into the epithilial cells

Question 4

What is the role of sodium-glucose co-transporter proteins?

Answer 4

They use facilitated diffusion to transport sodium ions and glucose molecules from the lumen into the epithelial cells

Question 5

What is the role of glucose protein channels?

Answer 5

They use facilitated diffusion to transport glucose molecules from the epithelial cells to the blood

Question 6

Describe the process of the co-transport of sodium and glucose

Answer 6

1) Sodium ions are actively transported out of the epithelial cells into the blood by the sodium-potassium pump
2) This creates a concentration gradient as there is now a higher concentration of sodium ions in the lumen than in the epithelial cells
3) Sodium ions diffuse from the lumen down their concentration gradient into the epithelial cells via the sodium-glucose co-transporter
4) Glucose from the lumen is also transported with the sodium ions against its concentration gradient, causing the concentration of glucose inside the epithelial cells to increase
5) Glucose will then diffuse out of the epithelial cells and into the blood down its concentration gradient via facilitated diffusion through the glucose protein channel