2) Sphingophospholipids The difference between the two classes of phospholipids - glycerophospholipids and sphingophospholipids - is that sphingophospholipids have a " __ backbone" instead of a glycerol backbone.

The difference between the two classes of phospholipids - glycerophospholipids and sphingophospholipids - is that sphingophospholipids have a **sphingosine backbone** instead of a glycerol backbone.