A plasma membrane torn by a fine microneedle reseals within seconds, with no enzyme adding new lipid. What drives this self-sealing?

Core Concept

A tear leaves hydrocarbon tails facing water, and ordering water cages around nonpolar surfaces carries a large entropy cost. To escape that penalty, lipids flow laterally and curl the free edges together until the tails bury themselves in a continuous bilayer again. The same hydrophobic effect that assembled the bilayer in the first place therefore repairs it, needing only thermal motion rather than new material or enzymatic help.