Answer to Question #341447 in Cell Biology for Triple X

Question

Describe the importance of selectively permeable membranes and compare the

functions of carrier proteins and channel proteins.

Answer 1

Selective permeability is a property of cellular membranes that only allows certain molecules to enter or exit the cell. This is important for the cell to maintain its internal order irrespective of the changes to the environment.  They are involved in the transport of substances that cannot pass through the lipid bilayer. Carrier proteins bind to ions or molecules of the substance they carry and deliver them into or out of the cell. They differ from channel proteins in that channel proteins are pore-forming proteins; they allow substances to pass through a water-filled pore, rather than capture and drag them to the other side of the membrane. Channel proteins transport substances down the concentration gradient. Carrier proteins transport substances both down and against the concentration gradient.  Channel proteins do not consume energy to transport molecules and ions down the concentration gradient. Carrier proteins need energy to transport substances against the concentration gradient. The transport of molecules and ions down the concentration gradient does not require energy.