1.3 b) Ion Transport and Generation of Ion Gradients

Question 1

All cells have an electrical ___ ___ across their plasma membrane

Answer 1

potential difference

Question 2

The electrical potential difference combines with the ___ ___ to form the ___ gradient.

Answer 2

concentration gradient, electrochemical

Question 3

The electrochemical gradient determines the transport of ___ within ___.

Answer 3

ions, cells

Question 4

A membrane potential is created when there is a difference in ___ ___ on the two sides of the ___.

Answer 4

electrical charge, membrane

Question 5

Ion pumps, such as the Na-K pump, use energy from the ___ of ___ to establish and maintain ___ ___.

Answer 5

hydrolysis of ATP, ion gradients

Question 6

The Na-K pump transports ___ against a steep ___ gradient, using energy from…

Answer 6

ions, steep, hydrolysis of ATP

Question 7

The Na-K pump (passively/actively) transports sodium ions ___ of the cell, and potassium ions ___ the cell.

Answer 7

(actively), out, into

Question 8

1/4
The Na-K pump has a high ___ for __ ions inside the cell.

Answer 8

affinity, sodium

Question 9

2/4
The sodium ions ___ to the pump, which is then ___ by ATP.

Answer 9

bind, phosphorylated

Question 10

3/4
This changes the ___ of the pump, simultaneously turning to face outside, whilst decreasing its ___ for sodium, allowing the sodium ions to be ___ out of the cell.

Answer 10

conformation, affinity, released

Question 11

4/4
Then __ ions bind to the ___ from outside the cell, and ____ occurs, changing the pump’s ____ and releasing the __ ions into the cell.

Answer 11

potassium, pump, dephosphorylation, conformation, potassium

Question 12

After each cycle, the pump’s conformation returns to its ___ state, so it is now able to bind to __ again.

Answer 12

original, Na

Question 13

How many sodium and potassium ions are transported in each cycle?

Answer 13

3 sodium and 2 potassium
(toucan = 2-k-in = 2 potassiums transported inside)

Question 14

Which two gradients does the Na-K pump establish and maintain?

Answer 14

concentration, electrical

Question 15

The sodium potassium pump is found in most ___ cells, and accounts for a high proportion of the ___ ___ ___ in many organisms.

Answer 15

animal, basal metabolic rate

Question 16

In the ___ ___, the sodium gradient created by the _ - _ ___ drives the active transport of ___.
Glucose is transported actively through a process called ___ ___.

Answer 16

small intestine, Na-K pump, glucose.
Glucose symport (it’s active because energy is used transporting sodium ions, which in turn transport glucose)

Question 17

In intestinal ___ cells, the Na-K pump generates a ___ ion gradient across the ___ ___.

Answer 17

epithelial, sodium, plasma membrane

Question 18

The glucose transporter responsible for glucose ___ transports ___ ions at the same time as ___, and in the same ___.

Answer 18

symport, sodium, glucose, direction

Question 19

Sodium ions are actively transported ___ of the cell (by the _ - _ pump) and then enter the cell, ___ their concentration gradient.
Glucose is simultaneously transported ___ the cell, ___ its concentration gradient.

Answer 19

out, (Na-K), down.
into, up

Question 20

the sodium potassium pump is also known as the Na/K ___

Answer 20

the Na/K-ATPase (its called this because it hydrolyses ATP itself - it does not use ATPases to hydrolyse ATP)

Question 21

Glucose symport is carried out through ___ proteins, that are positioned across the plasma membrane of cells bordering the ___ ___.

Answer 21

transporter, small intestine.

Question 22

The glucose travels from the ___ ___ into neighbouring ___ during glucose symport.

Answer 22

small intestine, cells.

Question 23

The concentration of __ ions, as well as the electrical ___ ___ across the membrane of these cells neighbouring the small intestine is maintained and regulated by the…

Answer 23

sodium, potential difference, Na/K pump!!

Question 24

Why must the concentration of sodium ions within the neighbouring cells be regulated by the Na/K pump?

Answer 24

because in order for glucose symport to work, the concentration of sodium ions within the neighbouring cells must be lower than in the small intestine, so that sodium can diffuse passively into the cells and transport glucose with it.

Question 25

What are epithelial cells?

Answer 25

Epithelial cells are a type of cell that covers the inside and outside of the surfaces of your body - eg intestinal epithelial cells border the intestine

Question 26

2020 P2 Q4.a)
Where there is a higher glucose concentration outside the cell, glucose molecules enter via passive transport. This is the case for fat and muscle cells.
Name the glucose transporter that enables glucose transport in these cells.

Answer 26

GLUT-4
(GLUT4 is carried inside vesicles to the cell membrane of the cell they’re in, in response to insulin binding to its extracellular receptor, and then the GLUT4 transports glucose in the bloodstream to fat and muscle cells. “GLUT4 is an insulin-regulated glucose transporter”)

Question 27

“GLUT4 is carried inside ___ from within cells to the cell membrane in response to ___ binding to its extracellular receptor. Then, GLUT4 transports ___ from the bloodstream into ___ and ___ cells where it is converted into glycogen.”

Answer 27

Vesicles, insulin, glucose, fat and muscle.