DNA replication


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DNA replication

The formation of new and, hopefully, identical copies of complete genomes. DNA replication occurs every time a cell divides to form two daughter cells. Under the influence of enzymes, DNA unwinds and the two strands separate over short lengths to form numerous replication forks, each of which is called a replicon. The separated strands are temporarily sealed with protein to prevent re-attachment. A short RNA sequence called a primer is formed for each strand at the fork. These primers provide a free 3'-OH end on which the new complementary sequence can be formed along the strand. The LEADING STRAND is synthesized continuously in the 5’ to 3’ direction, working towards the fork direction with removal of the RNA primers as the parental duplex is unwound. The LAGGING STRAND is synthesized discontinuously in the opposite direction as short fragments called Okazaki fragments. Lagging strand synthesis requires extension of the primer, then removal of the primers and gap filling. At least 20 different enzymes and factors, including DNA helicases, DNA polymerases, RNA primases, DNA TOPOISOMERASES and DNA ligases are involved in the complex process of DNA replication.

DNA replication

see DNA.
References in periodicals archive ?
This mechanism, mismatch repair, reduces the error frequency during DNA replication by about a thousandfold, according to the statement.
Ultraviolet rays permanently transmogrify these adjoining thymines into gnarled, double-looped structures that interfere with DNA replication and repair.
It is essential that this process is tightly and carefully regulated as errors in DNA replication are catastrophic, resulting in diseases like cancer.
Many anti-HIV drugs are designed to stop the process of DNA replication," said Dr.
is focused on developing SMAT products that bind to select DNA sequences and alter gene expression and DNA replication in pathogens.
Regulatory proteins bind to genomic DNA to control DNA replication and gene expression, thereby functioning as switches in the regulatory circuitry of cells.
We propose that this complex initiates DNA replication in yeast," Stillman says.
Food and Drug Administration, works by interrupting DNA replication, he explained.
This is important because, in human cells, the way in which the telomere tail is generated during DNA replication is likely to regulate the rate of telomere shortening.
The past few years have seen great progress in understanding eukaryotic DNA replication through the use of cell-free replication systems and reconstitution of individual steps in replication with purified proteins and naked DNA.
Coverage encompasses topics related to his investigations such as the therapy of neurodegeneration, herpesvirus DNA replication, cytomegalovirus control of cell death pathways, nucleotidylation to oncoapoptosis, and how herpesviruses and cells tussle to control autophagy.
Cancer arises from a single cell, which has mutated in a small number of genes because of random errors in the DNA replication process.