4.2 Diffusion

Question 1

What is diffusion

Answer 1

The net movement of molecules or ions from a region where they are highly concentrated to a region of lower concentration until evenly distributed

Question 2

What type of process is diffusion

Answer 2

Passive - no ATP required

Question 3

What is a ‘Passive’ process

Answer 3

A process that requires no ATP

Question 4

What is facilitated diffusion

Answer 4

Diffusion however it occurs at specific points on the plasma membrane where there are special protein molecules

Question 5

What are the two types of protein molecules involved in facilitated diffusion

Answer 5

1. Protein channels

2. Carrier proteins

Question 6

Describe the process by which facilitated diffusion occurs through protein channels

Answer 6

Protein channels are water-filled hydrophillic channels across the membrane.

They are selective, opening in the presence of a specific ion. The ion binds with the protein causing it to change shape in a way that closes it to one side of the membrane and opens it to the other side.

Question 7

Describe the process by which facilitated diffusion occurs with carrier proteins

Answer 7

When a molecule such as glucose that is specific to the protein is present, it binds with the protein. This causes it to change shape in such a way that the molecule is released to the inside of the membrane.

The only energy used is that of the molecules own kinetic energy