CAROL & MIKE WERNER / SCIENCE PHOTO LIBRARY CAROL & MIKE WERNER / SCIENCE PHOTO LIBRARY
From left: Larger molecules such as glucose use a specific transporter protein. Smaller molecules and ions can enter through a nonspecific transporter or channel. Soluble molecules and water can pass through the bilipid membrane by osmosis, or in the case of water, through a protein known as an aquaporin.
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