Answer:
The special structures in the cell membrane that allow materials such as water and sugar to pass through made of proteins.
Step-by-step explanation:
Proteins present on the cell membrane known as transmembrane protein. There are 3 main types of membrane proteins are found integral, peripheral and lipid-anchored proteins.
Some common functions of the membrane proteins includes:
1) They are working as ion channels, membrane receptor, G protein couple receptor and many types of transport proteins.
2) Membrane receptor which are present on the cell membrane can pass-on signal between internal and external environment of the cell.
3) Transporter is a type of membrane protein which helping in the movement of molecules across the membrane.