Social cells 2: ion channels

Question 1

Passive Transport

Answer 1

Transport that does not require ATP, e.g just diffusion through the bilayer or through protein channels (or facilitated diffusion)

Question 2

What is an example of a molecule that needs a carrier protein?

Answer 2

Glucose

Question 3

What are the limitations of facilitated diffusion?

Answer 3

Transport mechanism is specific
- Limited capacity
- Transport can be affected by competition

Question 4

What is Active transport?

Answer 4

Carrying molecules across a membrane using ATP (against the concentration gradient)

Question 5

What are the two mechanisms of active transport?

Answer 5

Primary and Secondary

Question 6

What does Uniporter mean?

Answer 6

One direction

Question 7

What does Symporter mean?

Answer 7

2 ions in the same direction

Question 8

What does Antiporter mean?

Answer 8

Multiple ions in different directions

Question 9

What is an example of primary transport?

Answer 9

Sodium

Question 10

What is an example of secondary active transport?

Answer 10

Glucose in the proximal distal tubule being taken up with sodium.

Question 11

Main notes about calcium pumps?

Answer 11

The cytosolic concentration needs to be kept low, and it uses ATP

Question 12

How do Ligand-Gated Channels work?

Answer 12

A ligand or messenger binds to the channel which causes a conformational change to the channel allowing ions to move through

Question 13

What is an example of a ligand-gated channel?

Answer 13

GPCR which can pull potassium channels into an ‘open’ state

Question 14

What is the GPCR channel in skeletal muscle called?

Answer 14

NACH receptor at neuromuscular junctions

Question 15

How do Voltage-gated channels work?

Answer 15

Change in voltage/ Depolarisation causes the channel to open

Question 16

How do leak channels work?

Answer 16

A pore in the membrane so they are always open, allows for movemnt of ions down conc gradient

Question 17

How do Stretch activated channels work?

Answer 17

Change in tension (Bilayer model) causes a conformational change in the membrane which pulls apart the channel

Question 18

How does the Tether model work?

Answer 18

They are anchored to the cytoskeleton, tension in the cytoskeleton causes the channel to be pulled open

Question 19

What are channels involved in?

Answer 19

• Muscle paralysis
• Heart disease
• Local anaesthetics

Question 20

Resting Membrane potential

Answer 20

the potential across the membrane when there is no action potential
being propagated

Question 21

What is an example of a leak channel?

Answer 21

potassium leak channel

Question 22

What is an example of a stretch-mediated channel?

Answer 22

Calcium activated potassium channel

Question 23

What does the Nernst equation determine?

Answer 23

The flow of individual ions across a membrane