Unit 1 - Topic 3 - Membrane Proteins - Section B - Ion transport pumps and generation of ion gradients

Question 1

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

Answer 1

The electrochemical gradient that determines the transport of the solute

Question 2

When is a membrane potential created

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

Ion pumps, such as what use what from the hydrolysis of ATP

Answer 3

Ion pumps, such as the sodium-potassium pump, use energy from the hydrolysis of ATP to establish and maintain ion gradients

Question 4

The sodium-potassium pump transports ions over what concentration gradient

Answer 4

Against a steep concentration gradient using energy directly from ATP hydrolysis

Question 5

Sodium-potassium pump transports what in which way

Answer 5

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

Question 6

Explain the transport of ions in a sodium-potassium pump

Answer 6

The pump has high affinity for sodium ions inside the cell; binding occurs; phosphorylation by ATP; conformation changes; affinity for sodium ions decreases; sodium ions released outside of the cell; potassium ions bind outside the cell; dephosphorylation; conformation changes; potassium ions taken into cell; affinity returns to start

Question 7

For each ATP hydrolysed how many sodium and potassium ions are transported and what does this establish

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

The sodium-potassium pump is found why and accounts for a high proportion of what

Answer 8

Is found in most animal cells, accounting for a high proportion of the basal metabolic rate in many organisms

Question 9

In the small intestine, the sodium gradient created by the sodium-potassium pump drives what

Answer 9

The active transport of glucose

Question 10

In which cells does the sodium-potassium pump generate a sodium ion gradient across the plasma membrane

Answer 10

In intestinal epithelial cells

Question 11

What is the glucose transporter responsible for

Answer 11

The glucose symport transports sodium ions and glucose at the same time and in the same direction

Question 12

How do glucose transports work

Answer 12

Sodium ions enter the cell down their concentration gradient; the simultaneous transport of glucose pumps glucose into the cell against its concentration gradient.