What Functions Do Membrane Proteins Serve

What functions do membrane proteins serve?

A) synthesize phospholipids for the maintenance and growth of the cell membrane
B) transport nutrients into the cell that cannot otherwise cross the phospholipid bilayer
C) transport wastes out of the cell that cannot otherwise cross the cell membrane
D) prevent small,uncharged substances from crossing the phospholipid bilayer
E) synthesize DNA within the cell using raw materials found outside the cell