All transport proteins span the most transport proteins change shape when they bind to a target molecule or molecules.

Answer;

-Cell membrane; bind

All transport proteins span the cell membrane. Most transport proteins change shape when they bind to a target molecule or molecules.

Explanation;

-Transport proteins are integral transmembrane proteins; that is they exist permanently within and span the membrane across which they transport substances.

-Transport proteins help molecules across the membrane via passive transport, a process called facilitated diffusion. These proteins are responsible for bringing in ions and other small molecules into the cell. Additionally, they allow for selective passage of specific molecules from the external environment. Each transport protein is specific to a certain molecule.

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