Final answer:
Attaching membrane proteins covalently to a phospholipid molecule is the least effective way to dampen the lateral diffusion of membrane proteins in lipid bilayers since phospholipids in the bilayer have mobility themselves.
Step-by-step explanation:
The least effective way to dampen the lateral diffusion of membrane proteins in lipid bilayers is by attaching membrane proteins covalently to a phospholipid molecule. This method does not restrict movement as effectively as the other options because the phospholipids themselves are able to move within the lipid bilayer. Therefore, while covalent attachment to a phospholipid can potentially influence diffusion, it does not provide the same level of restriction as tethering to static components such as the cell cortex or the extracellular matrix, or placing tight junctions in the membrane that act as barriers to diffusion.