Transport channels are made of what molecules?

Proteins.

Explanation:

They are called membrane proteins.

If you look at a picture of a cell membrane (http://apbiomaedahs.weebly.com/uploads/1/8/4/0/18405139/593679327_orig.jpg?510)
you'll see that there are 2 layers (bi- means 2) of the yellow things (the round heads are hydrophilic and the tails are hydrophobic and face each other), hence the name lipid bilayer