Question

How does facilitated diffusion differ from simple diffusion?

Answer 1

Simple diffusion differs from facilitated diffusion as it requires carrier or channel proteins for its movement.

Complete answer:
Diffusion is the movement of molecules from the high concentration to the low concentration without the expense of energy. There are two types of diffusion processes based on the presence of the facilitator molecule: facilitated diffusion and simple diffusion.

Simple diffusion is the unassisted movement of solute across the concentration gradient.
1)The speed of simple diffusion is relatively slow.
2)It occurs only in the direction of concentration gradient i.e. high to low concentration.
3)The simple diffusion process is not solute specific and is not affected by any inhibitor molecule.
4)Does not require any assistance molecule.
5)Simple diffusion is mostly involved in the passage of small nonpolar molecules.
6)The absorption of nutrients by the bacteria is an example of simple diffusion.

Facilitated diffusion is the assisted movement of solute across the membrane.
1)The speed of the facilitated diffusion is fast.
2)It can also occur against the concentration gradient.
3)This process is always solute specific and can be affected by the inhibitor molecules.
4)They require special proteins like carrier and channel proteins for the transport of solutes across the membrane.
5)Facilitated diffusion is commonly involved in the movement of large and polar molecules across a biological membrane.
6)Transfer of ions like calcium and potassium and the transport of amino acids and glucose from the blood to the cell are some examples of facilitated diffusion

Note: Simple diffusion is the passive process and does not require an ATP molecule while facilitated diffusion can be active or passive process i.e. may or may not require the ATP molecules as the carrier proteins required in the facilitated diffusion may sometimes require the ATP molecule.