Which biomolecule is structurally important to the cell membrane as it comprises the bilayer?

Phospholipids. Phospholipids, arranged in a bilayer, make up the basic fabric of the plasma membrane. They are well-suited for this role because they are amphipathic, meaning that they have both hydrophilic and hydrophobic regions. Chemical structure of a phospholipid, showing the hydrophilic head and hydrophobic tails ..

Closing a ring restricts the rotation around individual car bon carbon bonds hope it will you !