DNA replication

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[[DNA|DNA]] replication is a duplication process where exact copies of [[DNA]]&nbsp;within [[Cells|cells]] are replicated, with very low error rate. They typically occur at a rate of 1 in 10<sup>9</sup><sup></sup><sup></sup> bases per replication. In [[Mitosis]], DNA replication occurs during the [[S phase|S phase]]. DNA must be&nbsp;duplicated before the division takes place to main the chromosomal number of the two daughter cells. At the end of the division, two genetically identical daughter cells are formed.&nbsp;DNA replication is [[Semi-conservative]].  
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[[DNA|DNA]] replication is a duplication process where exact copies of [[DNA]]&nbsp;within [[Cells|cells]] are replicated, with very low error rate. They typically occur at a rate of 1 in 10<sup>9</sup><sup></sup><sup></sup> bases per replication. In [[Mitosis]], DNA replication occurs during the [[S phase|S phase]]. DNA must be&nbsp;duplicated before the division takes place to main the chromosomal number of the two daughter cells. At the end of the division, two genetically identical daughter cells are formed.&nbsp;DNA replication is called&nbsp;[[Semi-conservative replication|Semi-conservative&nbsp;replication]].  
  
 
=== Bacterial enzymes<br>  ===
 
=== Bacterial enzymes<br>  ===
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*[[DNA polymerase I|DNA Polymerase I]] - Catalyses&nbsp;the addition of short DNA&nbsp;fragments in place of&nbsp;now degraded [[Javascript:void(0);/*1354234678397*/|RNA&nbsp;primers]]; also got a&nbsp;proofreading via [[3' to 5' exonuclease]] activity (reduces the error rate<ref name="Topoisomerase" />)
 
*[[DNA polymerase I|DNA Polymerase I]] - Catalyses&nbsp;the addition of short DNA&nbsp;fragments in place of&nbsp;now degraded [[Javascript:void(0);/*1354234678397*/|RNA&nbsp;primers]]; also got a&nbsp;proofreading via [[3' to 5' exonuclease]] activity (reduces the error rate<ref name="Topoisomerase" />)
  
*[[Dna ligase|DNA Ligase]] - Joins&nbsp;[[Phosphate backbone]]&nbsp;at&nbsp;the&nbsp;lagging strand ([[Okazaki_fragments|Okazaki fragments]]<ref name="Topoisomerase" />)  
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*[[Dna ligase|DNA Ligase]] - Joins&nbsp;[[Phosphate backbone]]&nbsp;at&nbsp;the&nbsp;lagging strand ([[Okazaki fragments|Okazaki fragments]]<ref name="Topoisomerase" />)  
 
*[[Type II topoisomerase]] - Catalyses a reversible formation of a nick on 2 antiparallel DNA strands (at the same position on each). This allows produced circular DNA to escape from parental (segregation).&nbsp; Once again, nicks form at [[Phosphate backbones]]<ref name="Topoisomerase" />.  
 
*[[Type II topoisomerase]] - Catalyses a reversible formation of a nick on 2 antiparallel DNA strands (at the same position on each). This allows produced circular DNA to escape from parental (segregation).&nbsp; Once again, nicks form at [[Phosphate backbones]]<ref name="Topoisomerase" />.  
 
*[[DNA Polymerase II]] - Involved in DNA repair (e.g. during dimerisation of thymine bases via mutagens of radiation<ref>Berg, M. J., Tymoczko, J. L., and Stryer, L. (2002). Biochemistry. 2nd Edition. New York: Freeman and Co.</ref>)
 
*[[DNA Polymerase II]] - Involved in DNA repair (e.g. during dimerisation of thymine bases via mutagens of radiation<ref>Berg, M. J., Tymoczko, J. L., and Stryer, L. (2002). Biochemistry. 2nd Edition. New York: Freeman and Co.</ref>)

Revision as of 22:07, 23 November 2014

DNA replication is a duplication process where exact copies of DNA within cells are replicated, with very low error rate. They typically occur at a rate of 1 in 109 bases per replication. In Mitosis, DNA replication occurs during the S phase. DNA must be duplicated before the division takes place to main the chromosomal number of the two daughter cells. At the end of the division, two genetically identical daughter cells are formed. DNA replication is called Semi-conservative replication.

Bacterial enzymes

Unlike DNA replication in Eukaryotes (e.g. animals), Bacteria have a limited set of key enzymes associated with this process. These are enumerated below, according to their supposed chronological order during replication in E. coli.

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Cooper, G. M. (2000). The Cell: Molecular Approach. 2nd Edition. Washington, D.C: ASM Press.
  2. Messer, W., Blaesing, F., Majka, J., Nardmann, J., Schaper, S., Schmidt, A., Seitz, H., Speck, C., Tüngler, D., Wegrzyn, G., Weigel, C., Welzeck, M., Zakrzewska-Czerwinska, J.,(1999). Functional domains of DnaA proteins. Available at: http://www.sciencedirect.com/science/article/pii/S0300908499002151 (last assessed on 29/11/12).
  3. Benkovic, S. J, Valentine, A. M., and Salinas, F. (2001). Replisome-mediated DNA replication.
  4. Berg, M. J., Tymoczko, J. L., and Stryer, L. (2002). Biochemistry. 2nd Edition. New York: Freeman and Co.

 

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