A channel protein serves as a tunnel across the membrane into the cell. More specifically, channel proteins help molecules across the membrane via passive transport, a process called facilitated diffusion. These channel proteins are responsible for bringing in ions and other small molecules into the cell
During this process, they serve as a tunnel for certain ions and smallmolecules. Examples of channelproteins include chloride, sodium, calcium, and potassium ion channels. Carrier proteins are used in both passive and active transport and change shape as they move their particular molecule across the membrane.
