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In certain cell types, the telomerase enzyme can re-synthesize the telomere sequences, however, it is not present in all somatic cells. Once 25-50 divisions pass, the telomeres can be completely lost, inducing p53 to either permanently arrest the cell or induce apoptosis. Telomere shortening and p53 expression is a key mechanism to prevent ...
Telomerase, also called terminal transferase, [1] is a ribonucleoprotein that adds a species-dependent telomere repeat sequence to the 3' end of telomeres. 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 ...
For both budding yeast and mammals, the CST complex contributes to telomere maintenance, but this function is more crucial for budding yeast, where the CST complex performs the functions that shelterin performs in vertebrates. [1] At least four factors contribute to telomere maintenance: telomerase, shelterin, TERRA and the CST Complex. [5]
A telomere (/ ˈ t ɛ l ə m ɪər, ˈ t iː l ə-/; from Ancient Greek τέλος (télos) 'end' and μέρος (méros) 'part') is a region of repetitive nucleotide sequences associated with specialized proteins at the ends of linear chromosomes (see Sequences). Telomeres are a widespread genetic feature most commonly found in eukaryotes.
Shelterin (also called telosome) is a protein complex known to protect telomeres in many eukaryotes from DNA repair mechanisms, as well as to regulate telomerase activity. In mammals and other vertebrates, telomeric DNA consists of repeating double-stranded 5'-TTAGGG-3' (G-strand) sequences (2-15 kilobases in humans) along with the 3'-AATCCC-5' (C-strand) complement, ending with a 50-400 ...
This is known as the end replication problem. [1] The end replication problem is handled in eukaryotic cells by telomere regions and telomerase. Telomeres extend the 3' end of the parental chromosome beyond the 5' end of the daughter strand. This single-stranded DNA structure can act as an origin of replication that recruits telomerase.
Telomeres are sequences of repetitive nucleotides which serve no genetic use. During the replication process, the DNA replication enzymes are not able to copy the ending sequences at the telomere. Those sequences, located at the end of the telomere and chromosome, would hence get lost gradually. Once all of these sequences have been worn out ...
TERRA is RNA that is transcribed from telomeres — the repeating 6-nucleotide sequences that cap the ends of chromosomes. TERRA functions with shelterin to inhibit telomere lengthening by enzyme telomerase. [1] However, other studies have shown that under certain conditions TERRA can recruit telomerase to telomeres. [2]