What are the special structures in the cell membrane that allow materials such as water and sugar to pass through made of?

The special structures in the cell membrane that allow materials such as water and sugar to pass through made of proteins.

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.

the median of the data is 4.5.