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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) 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]
When the cell does this due to telomere-shortening, the ends of different chromosomes can be attached to each other. This solves the problem of lacking telomeres, but during cell division anaphase, the fused chromosomes are randomly ripped apart, causing many mutations and chromosomal abnormalities. As this process continues, the cell's genome ...
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 ...
Telomeres at the end of a chromosome. The relationship between telomeres and longevity and changing the length of telomeres is one of the new fields of research on increasing human lifespan and even human immortality. [1] [2] Telomeres are sequences at the ends of chromosomes that shorten with each cell division and determine the lifespan of ...
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 ...
Eukaryotes initiate DNA replication at multiple points in the chromosome, so replication forks meet and terminate at many points in the chromosome. Because eukaryotes have linear chromosomes, DNA replication is unable to reach the very end of the chromosomes. Due to this problem, DNA is lost in each replication cycle from the end of the chromosome.