DNA replication fork

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Introduction

The site at which DNA synthesis occurs. The fork is formed from unwinding of the original or template strands with synthesis of complementary DNA on the 2 template strands to form 2 double-stranded DNA molecules. Because DNA polymerase synthesizes DNA in the 5' to 3' direction, DNA synthesis on the 2 DNA strands at the replication fork differs. The leading strand is synthesized continuously, whereas the lagging strand is synthesized in fragments (Okazaki fragments) which are then ligated to created the appearance of chain elongation in the 3' to 5' direction.