Kaksireplikaatiohaara

Kaksireplikaatiohaara, also known as the replication fork, is a Y-shaped structure that forms during DNA replication. It is the site where the DNA double helix unwinds, allowing each strand to be used as a template for the synthesis of a new complementary strand.

The unwinding of the DNA helix is carried out by an enzyme called helicase. Helicase breaks the hydrogen bonds between the base pairs, separating the two strands of DNA. This separation creates the replication fork, with two single strands of DNA extending from the fork.

The process of DNA replication proceeds bidirectionally from origins of replication. At each origin, two replication forks are formed, moving in opposite directions. This allows for the rapid duplication of the entire genome.

The leading strand is synthesized continuously in the 5' to 3' direction, following the movement of the replication fork. The lagging strand, however, is synthesized discontinuously in short fragments called Okazaki fragments, also in the 5' to 3' direction, but in the opposite direction to the fork's movement. These fragments are later joined together by DNA ligase.

The accurate and efficient formation and movement of the replication fork are crucial for maintaining genomic integrity. Errors at the replication fork can lead to mutations and genomic instability, which can contribute to various diseases, including cancer.