Facilitated transport

Definition

Facilitated transport is a type of passive transport that involves the movement of molecules across a cell membrane via specific transmembrane proteins. It does not require energy and relies on concentration gradients to drive the process.

5 Must Know Facts For Your Next Test

1. Facilitated transport uses carrier proteins or channel proteins to move substances across cell membranes.
2. It is specific for certain molecules, such as glucose or ions like potassium and sodium.
3. This process is driven by the concentration gradient of the molecule being transported.
4. Facilitated diffusion can be saturated; once all transport proteins are occupied, increasing substrate concentration will not increase the rate of transport.
5. It allows polar and charged molecules, which cannot diffuse freely through the lipid bilayer, to cross the membrane.

Review Questions

• What role do transmembrane proteins play in facilitated transport?
• How does facilitated transport differ from simple diffusion?
• Why is facilitated transport considered a type of passive transport?

Related terms

PassiveTransport: A method of transporting materials across a cell membrane without using energy.

CarrierProteins: Transmembrane proteins that bind to specific molecules and change shape to shuttle them across the membrane.

ChannelProteins: Proteins that form pores in cell membranes, allowing specific ions or molecules to pass through by diffusion.