Ø考点1:末端复制问题 由于所有新的 DNA 合成启动都需要一条引物,这使线性染色体末端的复制成为难题,称为末端复制问题(end replication problem)。以前导链为模板的复制不存在这种问题,一条RNA引物即可指导DNA链的起始并能延伸到其模板的5’ 最末端。后随链合成需要多条引物,当起始最后一个冈崎片段合成的 RNA引物...
一、端粒与端粒酶 Ø考点1:末端复制问题 由于所有新的DNA合成启动都需要一条引物,这使线性染色体末端的复制成为难题,称为末端复制问题(end replication problem)。以前导链为模板的复制不存在这种问题,一条RNA引物即可指导DNA链的起始并能延伸到其模板的5...
SchematicdiagramofDNAreplicationatagrowingfork.LeadingStrandNucleotidesareaddedbyDNApolymerase（聚合酶）toeachdaughterstrandinthe5’→3’direction.SynthesisoftheleadingstrandoccurscontinuouslyfromasingleRNAprimeratits5’end.Laggingstrand(I)Synthesisoftheothernewstrandthelaggingstrandproceedsdiscontinuously,initiallyforming...
:Type II topoisomerases separate daughter DNA moleculesTopoisomerase II catalyze the decatenation of replication products.拓扑异构酶II催化复制产物的解环8.2 Finishing replication in eukaryotes:The end replication problemTelomere telomerase: a link with cancer and agingWhat is the end replication problem?
d, Excessive, but not normal levels of DNA pol III replication errors promote 3’-ssDNA-end foci. We manipulated levels of the ε subunit of pol III, encoded by the dnaQ gene, which performs replication “proofreading” (removal) of mis-incorporated bases in replication80. Deletion of dna...
In dividing somatic cells, telomeric regions become shortened due to the end-replication problem, stochastic deletion events and insufficient activity of telomerase, the reverse transcriptase present in germ, stem and most cancer cells that adds back a telomeric sequence1,2,3,4. Indeed, telomere ...
The DNA replication schemes of Figs. 72–76 obviate the end-replication problem that requires a telomerase-induced extension of G-rich telomeric sequences at the 3′ ends of linear DNA molecules (Blackburn and Szostak, 1984; Glieder and Blackburn, 1987; Forney et al., 1987; Moyzis et al....
a small problem arises. If you remember, I mentioned that the two strands run in the opposite directions. This means that when both strands are being synthesized in 5’ to 3’ direction, one will be moving in the direction of the replication fork while the other will move in the oppos...
Increased DNA damages would likely give rise to increased errors of replication past the damages (by trans-lesion synthesis) or increased error prone repair (e.g. by non-homologous end-joining), causing mutations. Increased mutations that activate oncogenes, inactivate tumor suppressor genes, cause...
Deoxyribonucleic acid replication is one of the vital parts of the central dogma and is essential for cell division. The replication follows different mechanisms in prokaryotes and eukaryotes.Answer and Explanation: The replication of the lagging strand of the DNA creates a...