DNA replication

 

1. Helicase opens up the DNA at the replication fork.

 2. Single-strand binding proteins coat the DNA around the replication fork to prevent rewinding of the DNA.

 3. Topoisomerase works at the region ahead of the replication fork to prevent supercoiling.

 4. Primase synthesizes RNA primers complementary to the DNA strand.

5. DNA polymerase III extends the primers, adding on to the 3' end, to make the bulk of the new DNA.

 6. RNA primers are removed and replaced with DNA by DNA polymerase I.

  7. The gaps between DNA fragments are sealed by DNA ligase.