Question

Why do molecules need a carrier protein?

Answer 1

Carrier protein:

1. Carrier protein is a type of facilitated diffusion as they have to cross the plasma membrane barrier, which goes down the concentration gradient.
2. Molecules which are hydrophilic are difficult to pass through the membrane due to the lipid content of the membrane.
3. Hence, hydrophilic molecules undergo facilitated diffusion.
4. Membrane proteins provide sites at which such molecules can cross the membrane.
5. Carrier proteins are also used in active transport against the concentration gradient.
6. Carrier proteins are specific for solutes.
7. It does not modify solutes and transports them unchanged.