Channel proteins

Definition

Channel proteins are integral membrane proteins that form pores in the plasma membrane, allowing specific molecules or ions to pass through by diffusion. They facilitate passive transport and do not require energy input from the cell.

5 Must Know Facts For Your Next Test

1. Channel proteins are involved in passive transport, which means they allow substances to move across the membrane without the use of cellular energy.
2. These proteins are highly selective, meaning only specific ions or molecules can pass through them based on size and charge.
3. Examples of channel proteins include aquaporins for water and ion channels for ions like Na+, K+, and Cl-.
4. Channel proteins can be gated, opening or closing in response to stimuli such as voltage changes or ligand binding.
5. They play a crucial role in maintaining homeostasis by regulating the movement of substances into and out of the cell.

Review Questions

• What is the primary function of channel proteins in the plasma membrane?
• How do channel proteins contribute to passive transport?
• Can channel proteins be gated? If so, what types of stimuli can cause them to open or close?

Related terms

Passive Transport:

Movement of molecules across cell membranes without energy input from the cell.

Aquaporins:

A type of channel protein specifically designed for transporting water molecules across cell membranes.

Ion Channels: Channel proteins that allow specific ions to enter or exit a cell, critical for functions such as nerve impulse transmission and muscle contraction.