DNA replication, removal of RNA primer

Definition

Target type: biologicalprocess

Removal of the Okazaki RNA primer from the lagging strand of replicating DNA, by a combination of the actions of DNA polymerase, DNA helicase and an endonuclease. [GOC:jl, PMID:12424238]

DNA replication is a complex process that involves the synthesis of a new DNA strand using an existing DNA strand as a template. This process is essential for cell division, as it ensures that each daughter cell receives a complete copy of the parent cell's genome. One of the key steps in DNA replication is the removal of RNA primers.

RNA primers are short stretches of RNA that are synthesized by an enzyme called primase. These primers provide a starting point for DNA polymerase, the enzyme that synthesizes new DNA strands. Once the DNA polymerase has added a few nucleotides to the primer, the primer is no longer needed and must be removed.

The removal of RNA primers is carried out by an enzyme called RNase H, which specifically degrades RNA. RNase H binds to the RNA primer and cleaves it into small fragments. These fragments are then removed by a special type of DNA polymerase called DNA polymerase I.

DNA polymerase I has a 5' to 3' exonuclease activity, which means that it can remove nucleotides from the 5' end of a DNA strand. This activity allows DNA polymerase I to remove the RNA primer fragments and replace them with DNA nucleotides.

Once the RNA primer has been removed, the gap left behind is filled in by DNA polymerase I. This process is called nick translation, as the nick (gap) is translated along the DNA strand as the primer is removed and replaced.

Finally, the newly synthesized DNA strand is joined to the rest of the DNA molecule by an enzyme called DNA ligase. DNA ligase forms a phosphodiester bond between the 3' hydroxyl group of the newly synthesized DNA strand and the 5' phosphate group of the existing DNA strand.

The removal of RNA primers is an essential step in DNA replication. Without it, the newly synthesized DNA strands would contain gaps and would be unable to function properly. This process ensures that the replicated DNA molecule is complete and accurate.'
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Proteins (4)

Compounds (10)