  The opening of the Y-fork - the first step of DNA replication - is shown to
be a critical phenomenon under an external force at one of its ends. From the
results of an equivalent delocalization in a non-hermitian quantum-mechanics
problem we show the different scaling behavior of unzipping and melting. The
resultant long-range critical features within the unzipped part of Y might play
a role in the highly correlated biochemical functions during replication.
