The replication of DNA in the cell is a vital process to life. Many enzymes and molecules are involved that not only copy a complete set of genetic information, but also double-check for errors along the way. The first step in this replication process is to unravel the DNA with the help of an enzyme known as helicase. This unwinding and separating of the two DNA strands produces what is known as a replication fork, where new DNA can be synthesized. Another enzyme, topoisomerase, allows the DNA to rotate during replication and helps relieve some of the physical strain on the double helix. Single stranded binding protein helps hold the two parent DNA strands apart during this time.
A primase adds an RNA primer to the strand of DNA available for replication so the next enzyme, DNA polymerase III, can carry out synthesis. DNA polymerase III works along both strands of parent DNA, adding base pairs off of the initial primers that were placed. While synthesizing, DNA polymerase III also checks for errors along the way, removing incorrectly paired bases and replacing them with correct ones. Once both strands have been replicated, DNA polymerase I replaces the initial RNA primers with the correct DNA sequence. Finally, DNA ligase seals the gaps between the bases.
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