Question
Which one of the following is correct for the transmembrane proteins in lipid bilayer of plasma membrane?
They are absent in animal cells
They act as channel proteins
They are absent in plant cells
They are only externally located
Solution
B.
They act as channel proteins
The tunnel proteins or transmembrane proteins run throughout the lipid bilayer and individually or in group form channels for the passage of water and water soluble substances. The channels however, possess selective properties for passage of different ions and other polar substances.
