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A DNA polymerase is a member of a family of enzymes that catalyze the synthesis of DNA molecules from nucleoside triphosphates, the molecular precursors of DNA. These enzymes are essential for DNA replication and usually work in groups to create two identical DNA duplexes from a single original DNA duplex.
"Link Between Long Telomeres and Long Life Is a Tall Tale, Study Finds". The New York Times. ISSN 0362-4331 "Long Telomeres, the Endcaps on DNA, Not the Fountain of Youth Once Thought — Scientists May Now Know Why". www.hopkinsmedicine.org; HannibalRodriguez (2019-08-15).
During DNA replication, DNA polymerase cannot replicate the sequences present at the 3' ends of the parent strands. This is a consequence of its unidirectional mode of DNA synthesis: it can only attach new nucleotides to an existing 3'-end (that is, synthesis progresses 5'-3') and thus it requires a primer to initiate
The two major protein complexes that bind to telomeric DNA in S. cerevisiae are: [citation needed] the Cdc13-Stn1-Ten1 (CST) complex, which binds the single-stranded DNA (ssDNA) of the 3' G-rich overhang at the end of the telomere, and; the Rif1-Rif2-Rap1 complex, which binds the double-stranded DNA (dsDNA) preceding the 3' overhang.
DNA polymerase I (or Pol I) is an enzyme that participates in the process of prokaryotic DNA replication. Discovered by Arthur Kornberg in 1956, [ 1 ] it was the first known DNA polymerase (and the first known of any kind of polymerase ).
This leads to an issue due to the fact that DNA polymerase is only able to add to the 3' end of the DNA strand. The 3'-5' action of DNA polymerase along the parent strand leaves a short single-stranded DNA (ssDNA) region at the 3' end of the parent strand when the Okazaki fragments have been repaired.
The polymerase is a monomeric protein with two distinct functional domains. Site-directed mutagenesis experiments support the proposition that this protein displays a structural and functional similarity to the Klenow fragment of the Escherichia coli Polymerase I enzyme; [3] it comprises a C-terminal polymerase domain and a spatially separated N-terminal domain with a 3'-5' exonuclease activity.
All cellular life forms and many DNA viruses, phages and plasmids use a primase to synthesize a short RNA primer with a free 3′ OH group which is subsequently elongated by a DNA polymerase. The retroelements (including retroviruses ) employ a transfer RNA that primes DNA replication by providing a free 3′ OH that is used for elongation by ...