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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 fruit fly Drosophila melanogaster lacks telomerase, but instead uses retrotransposons to maintain telomeres.
In this review, we focus on the structure, composition and function of telomerases. In addition, we discuss the origin and phylogenetic divergence of this unique RNA-dependent DNA polymerase as a witness of early eukaryotic evolution.
11 gru 2022 · Telomerase. The synthesis of a telomere involves a reverse transcriptase telomerase, which functions as an RNA-dependent DNA polymerase. Telomerase is present in germline and stem cells and has enhanced activity in cancer cells.
31 paź 2023 · DNA polymerase cannot replicate and repair DNA molecules at the ends of linear chromosomes. The ends of linear chromosomes, called telomeres, protect genes from getting deleted as cells continue to divide.
No doubt, DNA polymerase is not capable to completely copy DNA at the very ends of chromosomes; therefore, approximately 50 nucleotides are lost during each cell cycle, which results in gradual telomere length shortening. Critically short telomeres cause senescence, following crisis, and cell death.
8 paź 2020 · The maintenance of telomeres requires telomerase—a specific RNA-dependent DNA polymerase enzyme complex that carries its own RNA template and adds telomeric repeats to the ends of chromosomes using a reverse transcription mechanism.
17 maj 2018 · Telomerase is an RNA–protein complex (RNP) that extends telomeric DNA at the 3′ ends of chromosomes using its telomerase reverse transcriptase (TERT) and integral template-containing telomerase RNA (TER). Its activity is a critical determinant of human health, affecting aging, cancer, and stem cell renewal. Lack of atomic models of ...
