Facilitated Diffusion

Question 1

What is facilitated diffusion?

Answer 1

• The movement of large polar or charged molecules through the plasma membrane via channel or carrier proteins.

Question 2

How does facilitated diffusion happen through channel proteins?

Answer 2

• The membrane contains channel proteins through which polar molecules can pass.
• Membranes with protein channels are selectively permeable as most protein channels are specific to one molecule or ion.
• The more channel proteins, the higher the diffusion.

Question 3

How does facilitated diffusion happen through carrier proteins?

Answer 3

• Facilitated diffusion can involved carrier proteins which change the shape when a specific molecule binds
• In facilitated diffusion the movement of molecules is down a concentration gradient and does not require external energy.

Question 4

How does a glucose transporter work?

Answer 4

• The binding of glucose on the extracellular side changes the conformation of the glucose transporter.
• This change in the shape exposes the binding site to the cytosol.
• The glucose moves into body cells.

Question 5

What do processes depend on?

Answer 5

• They depend on membrane transport proteins which are regulated by controlling the number of transport proteins present in the membranes.

Question 6

What is co-transport?

Answer 6

• Two substances are required to bind in order for transport to occur.
• The transport proteins is known as the sodium-glucose cotransporter.

Question 7

Why are ions important?

Answer 7

• They allows for the formation of a concentration gradient between the extracellular fluid and the cytosol
• Ions are specific and only allow certain ions through the membranes.
• They go through gated or closed channels