Editing DNA replication (section)

{{short description|Biological process}}
[[File:DNA replication split.svg|thumb|200px|DNA replication: The [[double helix]] is 'unzipped' and unwound, then each separated strand (turquoise) acts as a template for replicating a new partner strand (green). [[Nucleotide]]s (bases) are matched to synthesize the new partner strands into two new double helices.]] 
In [[molecular biology]],<ref>{{Cite journal |vauthors=O'Donnell M, Langston L, Stillman B |date=July 2013 |title=Principles and concepts of DNA replication in bacteria, archaea, and eukarya |journal=Cold Spring Harbor Perspectives in Biology |volume=5 |issue=7 |pages=a010108 |doi=10.1101/cshperspect.a010108 |pmc=3685895 |pmid=23818497}}</ref><ref>{{Cite journal |vauthors=Prioleau MN, MacAlpine DM |date=August 2016 |title=DNA replication origins-where do we begin? |journal=Genes & Development |volume=30 |issue=15 |pages=1683–1697 |doi=10.1101/gad.285114.116 |pmc=5002974 |pmid=27542827}}</ref><ref>{{Cite journal |vauthors=Dewar JM, Walter JC |date=August 2017 |title=Mechanisms of DNA replication termination |journal=Nature Reviews. Molecular Cell Biology |volume=18 |issue=8 |pages=507–516 |doi=10.1038/nrm.2017.42 |pmc=6386472 |pmid=28537574}}</ref> '''DNA replication''' is the [[biological process]] of producing two identical replicas of DNA from one original [[DNA]] molecule.<ref>{{Cite web |date=2022-03-01 |title=What Is DNA Replication And Its Steps? |url=https://www.funbiology.com/what-is-dna-replication/ |access-date=2023-08-04 |language=en-US |vauthors=Sabhadiya A}}</ref> DNA replication occurs in all [[life|living organisms]], acting as the most essential part of [[heredity|biological inheritance]]. This is essential for [[cell division]] during growth and repair of damaged tissues, while it also ensures that each of the new cells receives its own copy of the DNA.<ref>{{Cite web |title=GENETICS / DNA REPLICATION (BASIC) – Pathwayz |url=https://www.pathwayz.org/Tree/Plain/DNA+REPLICATION+(BASIC)#:~:text=The%20purpose%20of%20DNA%20replication,own%20copy%20of%20the%20DNA. |access-date=2020-12-10 |website=pathwayz.org}}</ref> The cell possesses the distinctive property of division, which makes replication of DNA essential.

DNA is made up of a [[nucleic acid double helix|double helix]] of two [[Complementary DNA|complementary]] [[DNA strand|strands]]. DNA is often called double helix. The double helix describes the appearance of a double-stranded DNA which is composed of two linear strands that run opposite to each other and twist together.<ref>{{Cite web |title=double helix |url=https://www.nature.com/scitable/definition/double-helix-277/ |access-date=2020-12-10 |website=Learn Science at Scitable |publisher=Nature Education}}</ref> During replication, these strands are separated. Each strand of the original DNA molecule then serves as a template for the production of its counterpart, a process referred to as [[semiconservative replication]]. As a result, the new helix will be composed of an original DNA strand as well as a newly synthesized strand.<ref>{{Cite journal |vauthors=Pray LA |date=2008 |title=Semi-Conservative DNA Replication; Meselson and Stahl |url=https://www.nature.com/scitable/topicpage/semi-conservative-dna-replication-meselson-and-stahl-421/ |journal=Nature Education |volume=1 |issue=1 |page=98}}</ref> Cellular [[Proofreading (Biology)|proofreading]] and error-checking mechanisms ensure near perfect [[fidelity]] for DNA replication.<ref name="Berg">Imperfect DNA replication results in [[mutation]]s. {{Cite book |url=https://archive.org/details/biochemistrychap00jere |title=Biochemistry |vauthors=Berg JM, Tymoczko JL, Stryer L, Clarke ND |publisher=W.H. Freeman and Company |year=2002 |isbn=0-7167-3051-0 |chapter=Chapter 27: DNA Replication, Recombination, and Repair |access-date=2019-08-09 |chapter-url=https://www.ncbi.nlm.nih.gov/books/bv.fc,kgi?rid=stryer.chapter.3740 |archive-url=https://web.archive.org/web/20200326053135/https://archive.org/details/biochemistrychap00jere |archive-date=2020-03-26}}</ref><ref name="Alberts">{{Cite book |title=Molecular Cell Biology |vauthors=Lodish H, Berk A, Zipursky SL, etal |publisher=WH Freeman |year=2000 |isbn=0-7167-3136-3 |edition=4th |chapter=DNA Replication, Repair, and Recombination |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK21656/}}</ref>

In a [[cell (biology)|cell]], DNA replication begins at specific locations ([[origin of replication|origins of replication]])<ref name="Hu 352–372">{{Cite journal |vauthors=Hu Y, Stillman B |date=February 2023 |title=Origins of DNA replication in eukaryotes |journal=Molecular Cell |volume=83 |issue=3 |pages=352–372 |doi=10.1016/j.molcel.2022.12.024 |pmc=9898300 |pmid=36640769}}</ref> in the [[genome]]<ref name="origins">{{Cite book |url=https://archive.org/details/biochemistrychap00jere |title=Biochemistry |vauthors=Berg JM, Tymoczko JL, Stryer L, Clarke ND |publisher=W.H. Freeman and Company |year=2002 |isbn=0-7167-3051-0 |chapter=Chapter 27, Section 4: DNA Replication of Both Strands Proceeds Rapidly from Specific Start Sites |access-date=2019-08-09 |chapter-url=https://www.ncbi.nlm.nih.gov/bofghoks/bv.fcvbngi?rid=stayer.section.3794 |archive-url=https://web.archive.org/web/20200326053135/https://archive.org/details/biochemistrychap00jere |archive-date=2020-03-26}}</ref> which contains the genetic material of an organism.<ref>{{Cite web |title=What is a genome? |url=https://www.yourgenome.org/theme/what-is-a-genome/ |access-date=2025-03-24 |website=yourgenome |language=en}}</ref> Unwinding of DNA at the origin and synthesis of new strands, accommodated by an [[enzyme]] known as [[helicase]], results in [[replication fork]]s growing bi-directionally from the origin. A number of [[protein]]s are associated with the replication fork to help in the initiation and continuation of [[DNA synthesis]]. Most prominently, [[DNA polymerase]] synthesizes the new strands by adding [[nucleotide]]s that complement each (template) strand. DNA  replication occurs during the S-stage of [[interphase]].<ref>{{Cite journal |last1=Chagin |first1=Vadim O. |last2=Stear |first2=Jeffrey H. |last3=Cardoso |first3=M. Cristina |date=April 2010 |title=Organization of DNA replication |journal=Cold Spring Harbor Perspectives in Biology |volume=2 |issue=4 |pages=a000737 |doi=10.1101/cshperspect.a000737 |issn=1943-0264 |pmc=2845211 |pmid=20452942}}</ref>

DNA replication (DNA amplification) can also be performed ''[[in vitro]]'' (artificially, outside a cell).<ref name="Jarillo-2021">{{Cite journal |vauthors=Jarillo J, Ibarra B, Cao-García FJ |date=2021 |title=DNA replication: ''In vitro'' single-molecule manipulation data analysis and models |journal=Computational and Structural Biotechnology Journal |volume=19 |pages=3765–3778 |doi=10.1016/j.csbj.2021.06.032 |pmc=8267548 |pmid=34285777}}</ref> DNA polymerases isolated from cells and artificial DNA primers can be used to start DNA synthesis at known sequences in a template DNA molecule. [[Polymerase chain reaction]] (PCR), [[ligase chain reaction]] (LCR), and [[transcription-mediated amplification]] (TMA) are examples. In March 2021, researchers reported evidence suggesting that a preliminary form of [[transfer RNA]], a necessary component of [[Translation (biology)|translation]], the biological synthesis of new [[protein]]s in accordance with the [[genetic code]], could have been a replicator molecule itself in the very early development of life, or [[abiogenesis]].<ref name="EL-20210302">{{Cite journal |vauthors=Kühnlein A, Lanzmich SA, Braun D |date=March 2021 |title=tRNA sequences can assemble into a replicator |journal=eLife |volume=10 |pages=e63431 |doi=10.7554/eLife.63431 |pmc=7924937 |pmid=33648631 |doi-access=free}}</ref><ref name="STD-20210403">{{Cite news |date=3 April 2021 |title=Solving the Chicken-and-the-Egg Problem – "A Step Closer to the Reconstruction of the Origin of Life" |url=https://scitechdaily.com/solving-the-chicken-and-the-egg-problem-a-step-closer-to-the-reconstruction-of-the-origin-of-life/ |access-date=3 April 2021 |work=[[SciTech (magazine)|SciTechDaily]] |vauthors=Maximilian L}}</ref>