Co-transport of glucose
A Sodium-potassium
pump is an active
transport mechanism
1
which uses or the
3
body’s ATP. It carries
out the co-transport
+¿ ¿ +¿ ¿
of N a and K
ions using ATP
+¿ ¿
1) 3 N a ions and a molecule of ATP bind to the pump
2) This causes the pump to change shape, and breaks the ATP into a phosphate ion and ADP.
The ADP is released and the phosphate remains attached.
+¿ ¿ +¿ ¿
3) The N a ions are released outside the cell, and 2 K ions bind to the pump
+¿ ¿
4) This causes the pump to change shape, releasing the phosphate and K ions.
An epithelial (intestinal) cell has sodium-
+¿ ¿
potassium pumps which move N a ions out of
the cell into the blood, creating a concentration
+¿ ¿
gradient of N a from the lumen to the cell.
N a Ions pull glucose molecules with them
+¿ ¿
when they diffuse into the cell through channel
proteins (co-transport). Dynamic equilibrium isn’t
+¿ ¿
reached because the N a ions are constantly
being removed by the sodium-potassium pumps.
Adding glucose to the cell creates a concentration gradient from the cell to the blood, so the glucose
enters the blood by facilitated diffusion through carrier proteins.
A sodium-potassium pump is also used during the co-transport of amino acids. Different channel
proteins are needed for the co-transport and facilitated diffusion steps of the process as amino acids
are a different shape to glucose.
A Sodium-potassium
pump is an active
transport mechanism
1
which uses or the
3
body’s ATP. It carries
out the co-transport
+¿ ¿ +¿ ¿
of N a and K
ions using ATP
+¿ ¿
1) 3 N a ions and a molecule of ATP bind to the pump
2) This causes the pump to change shape, and breaks the ATP into a phosphate ion and ADP.
The ADP is released and the phosphate remains attached.
+¿ ¿ +¿ ¿
3) The N a ions are released outside the cell, and 2 K ions bind to the pump
+¿ ¿
4) This causes the pump to change shape, releasing the phosphate and K ions.
An epithelial (intestinal) cell has sodium-
+¿ ¿
potassium pumps which move N a ions out of
the cell into the blood, creating a concentration
+¿ ¿
gradient of N a from the lumen to the cell.
N a Ions pull glucose molecules with them
+¿ ¿
when they diffuse into the cell through channel
proteins (co-transport). Dynamic equilibrium isn’t
+¿ ¿
reached because the N a ions are constantly
being removed by the sodium-potassium pumps.
Adding glucose to the cell creates a concentration gradient from the cell to the blood, so the glucose
enters the blood by facilitated diffusion through carrier proteins.
A sodium-potassium pump is also used during the co-transport of amino acids. Different channel
proteins are needed for the co-transport and facilitated diffusion steps of the process as amino acids
are a different shape to glucose.
