What is the function of exonuclease in DNA replication?
Exonucleases can act as proofreaders during DNA polymerisation in DNA replication, to remove unusual DNA structures that arise from problems with DNA replication fork progression, and they can be directly involved in repairing damaged DNA.
What is exonuclease activity used for?
However, the main function of the 5′ to 3′ exonuclease activity is to remove ribonucleotide primers that are used in DNA replication. Pol I can add nucleotides to a 3′-OH group at a single-strand (a nick) in a double helix.
What is meant by exonuclease?
Exonucleases are enzymes that work by cleaving nucleotides one at a time from the end (exo) of a polynucleotide chain. A hydrolyzing reaction that breaks phosphodiester bonds at either the 3′ or the 5′ end occurs.
What is the difference between exonuclease and endonuclease activity?
An endonuclease is a group of enzymes that cleave the phosphodiester bond present within a polynucleotide chain. Exonucleases are enzymes that cleave DNA sequences in a polynucleotide chain from either the 5′ or 3′ end one at a time. Endonucleases cleave the nucleotide sequence from the middle.
What joins Okazaki fragments together?
On the leading strand, DNA synthesis occurs continuously. On the lagging strand, DNA synthesis restarts many times as the helix unwinds, resulting in many short fragments called “Okazaki fragments.” DNA ligase joins the Okazaki fragments together into a single DNA molecule.
Where are Okazaki fragments formed?
Okazaki fragments are formed on lagging strands, initiated by the creation of a new RNA primer by the primosome. Okazaki fragments are formed on the lagging strand for the synthesis of DNA in 5′ to 3′ direction towards the replication fork.
What if DNA ligase is inhibited?
iii) When DNA ligase is inhibited, it differentially affects the synthesis from the leading and the lagging strands. The lagging strand is more affected by the lack of DNA ligase. DNA replication on the lagging strand occurs in small stretches called Okasaki fragments.
Is Primase used in translation?
Primase is the enzyme that synthesizes RNA primers, oligonucleotides that are complementarily bound to a nucleic acid polymer. The bacterial primase gene, dnaG, is the central gene of the macromolecular synthesis operon carrying the genes for the initiation phases of translation, replication, and transcription.