What is the role of exonuclease?
Exonucleases are key enzymes involved in many aspects of cellular metabolism and maintenance and are essential to genome stability, acting to cleave DNA from free ends.
What is the difference between endonucleases and Exonucleases?
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.
How are RNA primers removed and replaced by DNA?
The RNA primers are removed and replaced by DNA through the activity of DNA polymerase I, the other polymerase involved in replication. The nicks that remain after the primers are replaced get sealed by the enzyme DNA ligase.
Are primers RNA or DNA?
A primer is a short nucleic acid sequence that provides a starting point for DNA synthesis. In living organisms, primers are short strands of RNA. A primer must be synthesized by an enzyme called primase, which is a type of RNA polymerase, before DNA replication can occur.
Why are 2 primers needed for PCR?
Two primers are used in each PCR reaction, and they are designed so that they flank the target region (region that should be copied). That is, they are given sequences that will make them bind to opposite strands of the template DNA, just at the edges of the region to be copied.
Why does DNA polymerase 3 need a primer?
DNA polymerases add nucleotides to the 3′ end of a polynucleotide chain. To initiate this reaction, DNA polymerases require a primer with a free 3′-hydroxyl group already base-paired to the template. They cannot start from scratch by adding nucleotides to a free single-stranded DNA template.