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Human chromosomes (grey) capped by telomeres (white). 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 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 ...
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. [2]
This problem makes eukaryotic cells unable to copy the last few bases on the 3' end of the template DNA strand, leading to chromosome—and, therefore, telomere—shortening every S phase. [2] Measurements of telomere lengths across cell types at various ages suggest that this gradual chromosome shortening results in a gradual reduction in ...
Telomeres are DNA tandem repeats at the end of chromosomes that shorten during each cycle of cell division. [27] Recently, the role of telomeres in cellular senescence has aroused general interest, especially with a view to the possible genetically adverse effects of cloning .
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 ...
However, because chromosomes have telomeres or mega-telomeres on their ends, repetitive non-essential sequences of DNA are lost instead (See: Telomere shortening). [2] [3] While the chromosomes in most eukaryotic organisms are capped with telomeres, mega-telomeres are only found in a few species, such as mice [4] and some birds. [5]
At each end of a chromosome lies a "cap" or telomere, as it is known, which protects it. After Elizabeth Blackburn discovered that telomeres have a particular DNA, through experiments conducted on ciliates and yeast, she and Jack Szostak proved in 1982 that the telomeres' DNA prevents chromosomes from being broken down,