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Furthermore, it was predicted that a specialized DNA polymerase (originally called a tandem-DNA-polymerase) could extend telomeres in immortal tissues such as germ line, cancer cells and stem cells. It also followed from this hypothesis that organisms with circular genome, such as bacteria, do not have the end replication problem and therefore ...
As telomeres shorten as a natural consequence of repeated cell division or due to other factors, such as oxidative stress, [19] shelterin proteins lose the ability to bind to telomeric DNA. When telomeres reach a critically short length, sufficient shelterin proteins to inhibit checkpoint activation are not available, although NHEJ and HR ...
A telomere is a region of repetitive sequences at each end of the chromosomes of most eukaryotes. Telomeres protect the end of the chromosome from DNA damage or from fusion with neighbouring chromosomes.
The typical normal human fetal cell will divide between 50 and 70 times before experiencing senescence. As the cell divides, the telomeres on the ends of chromosomes shorten. The Hayflick limit is the limit on cell replication imposed by the shortening of telomeres with each division. This end stage is known as cellular senescence.
In the 1950s, Barbara McClintock first observed DNA transposition and illustrated the functions of the centromere and telomere at the Cold Spring Harbor Symposium. [4] McClintock's work set the stage for the discovery of repeated sequences because transposition, centromere structure, and telomere structure are all possible through repetitive ...
(a) Schematic of conservative replication of DNA by break-induced telomere synthesis. (b) Four potential sources of DNA/telomere sequence that can be copied during new telomere synthesis by ALT [1] The main alternative lengthening mechanism for telomeres is a type of homologous recombination called Break-induced Telomere Synthesis (or BITS). [1]
Therefore, TERRA expression may play an important role in the proper orchestration of DNA replication, as TERRA may hybridize with single-stranded DNA during replication. [ 21 ] [ 26 ] [ 27 ] [ 28 ] In cells with long telomeres and high TERRA expression, this could potentially lead to replicative arrest and the eventual collapse of the ...
Eukaryotic DNA replication is a conserved mechanism that restricts DNA replication to ... Telomeres extend the 3' end of the parental chromosome beyond the 5' end of ...