What would happen if, in the course of replication, the topoisomerases were unable to reattach the DNA fragments of each strand after unwinding (relaxing) the DNA molecule?
Full Answer
Topoisomerase alleviates supercoiling downstream of the origin of replication. In the absence of topoisomerase, supercoiling tension would increase to the point where DNA could fragment. DNA replication could not be initiated because there would be no RNA primer. DNA strands would not be ligated together.
(a) If topoisomerase was not available for DNA replication the strands would not be able to relieve the tension created by helicase untwisting them. This may destabilize the strand and prevent binding and proper manipulation by other replication enzymes.
function in DNA replication A class of enzymes called DNA topoisomerases removes helical twists by cutting a DNA strand and then resealing the cut. Enzymes called helicases then separate the two strands of the double helix, exposing two template surfaces for the alignment of free nucleotides.
The main function of the third polymerase, Pol III, is duplication of the chromosomal DNA, while other DNA polymerases are involved mostly in DNA repair and translesion DNA synthesis. Together with a DNA helicase and a primase, Pol III HE participates in the replicative apparatus that acts at the replication fork.
Topoisomerases. DNA topoisomerases are able to solve topological problems resulting from replication, transcription, recombination, and reorganization of the chromatin. Further on, topoisomerases change the state of supercoiling of the DNA and therefore, have great impact on gene activity.
iii) When DNA ligase is inhibited, it differentially affects the synthesis from the leading and the lagging strands.Mar 17, 2004
What is the function of the enzyme topoisomerase in DNA replication? relieving strain in the DNA ahead of the replication fork caused by the untwisting of the double helix (Topoisomerases are enzymes that participate in the over winding or underwinding of DNA.
Topoisomerase II is a ubiquitous enzyme that is essential for the survival of all eukaryotic organisms and plays critical roles in virtually every aspect of DNA metabolism. The enzyme unknots and untangles DNA by passing an intact helix through a transient double-stranded break that it generates in a separate helix.Oct 1, 1998
Topoisomerase breaks a covalent bond in the backbone of one parental strand. ( Topoisomerase relieves the strain caused by unwinding of the DNA by helicase.
The polymerase checks whether the newly-added base has paired correctly with the base in the template strand. If it is the correct base, the next nucleotide is added. If an incorrect base has been added, the enzyme makes a cut at the phosphodiester bond and releases the incorrect nucleotide.
DNA polymerase III adds DNA nucleotides to the primer(s), synthesizing the DNA of both the leading and the lagging strands.
DNA polymerase III holoenzyme is the enzyme primarily responsible for replicative DNA synthesis in E. coli. It carries out primer-initiated 5' to 3' polymerization of DNA on a single-stranded DNAtemplate, as well as 3' to 5' exonucleolytic editing of mispaired nucleotides.