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Telomerase restores short bits of DNA known as telomeres, which are otherwise shortened after repeated division of a cell via mitosis. In normal circumstances, where telomerase is absent, if a cell divides recursively, at some point the progeny reach their Hayflick limit , [ 26 ] which is believed to be between 50 and 70 cell divisions.
Eukaryotic DNA replication is a conserved mechanism that restricts ... This single-stranded DNA structure can act as an origin of replication that recruits telomerase ...
Replication Factories Disentangle Sister Chromatids. The disentanglement is essential for distributing the chromatids into daughter cells after DNA replication. Because sister chromatids after DNA replication hold each other by Cohesin rings, there is the only chance for the disentanglement in DNA replication. Fixing of replication machineries ...
Lagging strand during DNA replication. During DNA replication, DNA polymerase cannot replicate the sequences present at the 3' ends of the parent strands. This is a consequence of its unidirectional mode of DNA synthesis: it can only attach new nucleotides to an existing 3'-end (that is, synthesis progresses 5'-3') and thus it requires a primer ...
Telomerase can be reactivated and telomeres restored to the embryonic state by somatic cell nuclear transfer. [18] The continuous shortening of telomeres with each replication in somatic (body) cells may play a role in aging [19] and in cancer prevention.
The two major protein complexes that bind to telomeric DNA in S. cerevisiae are: [citation needed] the Cdc13-Stn1-Ten1 (CST) complex, which binds the single-stranded DNA (ssDNA) of the 3' G-rich overhang at the end of the telomere, and; the Rif1-Rif2-Rap1 complex, which binds the double-stranded DNA (dsDNA) preceding the 3' overhang.
Telomerase is a ribonucleoprotein polymerase that maintains telomere ends by addition of the telomere repeat TTAGGG. The enzyme consists of a protein component with reverse transcriptase activity, encoded by this gene, and an RNA component that serves as a template for the telomere repeat.
During the process of DNA replication of a chromosome, small segments of DNA within each telomere are unable to be copied and are lost. [10] This occurs due to the uneven nature of DNA replication, where leading and lagging strands are not replicated symmetrically. [11]