Ion Transport Pumps And Generation Of Ion Gradients

Question 1

For a solute carrying a net charge what does the concentration gradient and electrical potential difference combine to form?

Answer 1

The electrochemical gradient that determines the transport of the solute

Question 2

How is a membrane potential created?

Answer 2

When there is a difference in electrical charge on the two sides of the membrane

Question 3

Why do ion pumps such as the Na/K pump use energy from the hydrolysis of ATP?

Answer 3

To establish and maintain ion gradients

Question 4

How does the Na/K pump transport ions against a steep concentration gradient?

Answer 4

Using energy directly from ATP hydrolysis

Question 5

What goes in and out of the cell using the Na/K pump?

Answer 5

It actively transports sodium ions out of the cell and potassium ions into the cell

Question 6

How does the Na/K pump work?

Answer 6

The pump has a high affinity for sodium ions inside the cell therefore binding occurs. The pump hydrolyses ATP and phosphate attaches to it. Phosphorylation by ATP causes the conformation of the protein to change. The affinity for sodium ions decreases resulting in sodium being released outside of the cell. The pump now has high affinity for potassium ions outside the cell therefore binding occurs. Dephosphorylation occurs which causes the conformation of the protein to change. Potassium ions are taken into the cell and the affinity returns to the start

Question 7

What happens for each ATP hydrolysed and why?

Answer 7

Three sodium ions are transported out of the cell and two potassium ions are transported into the cell. This establishes both concentration gradients and an electrical gradient

Question 8

Why is the Na/K pump found in most animal cells?

Answer 8

To account for a high proportion of the basal metabolic rate in many organisms

Question 9

What does the sodium gradient created in the small intestine by the Na/K pump do?

Answer 9

It drives the active transport of glucose

Question 10

In intestinal epithelial cells what does the Na/K pump generate?

Answer 10

A sodium ion gradient across the plasma membrane

Question 11

What does the glucose transporter responsible for glucose symport, transport?

Answer 11

Sodium ions and glucose at the same time and in the same direction. Sodium ions enter the cell down their concentration gradient and the simultaneous transport of glucose pumps glucose into the cell against its concentration gradient