Protein Transport and Diffusion – Key Points

Protein-mediated transport

• Transport across membranes largely uses proteins; the cell regulates how much of each transport protein is present in the membrane.

Oxygen and carbon dioxide diffusion

• $O<em>{2}$ and $CO</em>{2}$ move by simple diffusion (no transport proteins).

Facilitated diffusion

• Other solutes are transported via transport proteins (facilitated diffusion).
• Solutes bind in a hydrophilic pocket within the transporter.