Ion Transport Pumps and Generation of Ion Gradients

Question 1

Electrochemical gradient

Answer 1

For a solute carrying a net charge, the concentration gradient and the electrical potential difference combine to form the electrochemical gradient that determines the transport of the solute

Question 2

A membrane potential

(an electrical potential difference)

Answer 2

A membrane potential (an electrical potential difference) is created when there is a difference in electrical charge on the two sides of the membrane.

Question 3

Sodium-potassium pump

Answer 3

The sodium-potassium pump transports ions
against a steep concentration gradient using
energy directly from ATP hydrolysis

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

Question 4

Sodium-potassium pump

Answer 4

The sodium-potassium pump transports ions against a steep concentration gradient using energy directly from ATP hydrolysis

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

The sodium-potassium pump is found in most animal cells, accounting for a high proportion of the basal metabolic rate in many organisms

Question 5

Sodium-potassium pump in small intestine

Answer 5

In the small intestine, the sodium gradient created by the sodium-potassium pump drives the active transport of glucose

In intestinal epithelial cell, the sodium-potassium pump generates a sodium ion gradient across the plasma membrane

The glucose transporter responsible for this glucose symport, transports sodium ions and glucose at the same time and in the same direction.

As the sodium ions enter the cell down their concentration gradient, the simultaneous transport of glucose pumps glucose into the cell against its concentration gradient.