which of the following is a protein that could not be found in the cell membrane? A non-gated An enzyme of the electron transport chain A glucose transporter. A major histocompatibility Complex (MHC) protein.v The receptor for insulin. Oxygen (O_(2)) gas moves across a cell membrane by simple diffusion. facilitated I transport. a process that moves it from a low concentration to a high concentration. facilitated diffusion. endocytosis.

* **Which of the following is a protein that could *not* be found in the cell membrane?** An enzyme of the electron transport chain. These enzymes are located within the inner mitochondrial membrane, not the cell membrane. All the other options are membrane proteins:<br /><br /> * Non-gated ion channels are integral membrane proteins.<br /> * Glucose transporters are transmembrane proteins.<br /> * MHC proteins are embedded in the cell membrane.<br /> * Insulin receptors are transmembrane proteins.<br /><br />* **Oxygen ($O_{2}$) gas moves across a cell membrane by:** simple diffusion. Oxygen is small and nonpolar, allowing it to freely diffuse across the lipid bilayer without the assistance of any proteins or energy expenditure.<br />