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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).
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 .
TERRA-Telomerase Interaction at Long Telomeres. At cells with long telomeres, TERRA is proposed to act as a negative regulator of telomerase activity. This direct inhibitor function acts through base-pairing of the tandem repeats found throughout TERRA's 3'-end to the complementary RNA template region of telomerase. [6]
Almost all cancer cells have shortened telomeres. [20] This may seem counter-intuitive, as short telomeres should activate the ATR/ATM DNA damage checkpoint and thereby prevent division. Resolving the question of why cancer cells have short telomeres led to the development of a two-stage model for how cancer cells subvert telomeric regulation ...
Repeated sequences (also known as repetitive elements, repeating units or repeats) are short or long patterns that occur in multiple copies throughout the genome.In many organisms, a significant fraction of the genomic DNA is repetitive, with over two-thirds of the sequence consisting of repetitive elements in humans. [1]
Telomeres are regions of repetitive DNA at the end of a chromosome, which provide protection from chromosomal deterioration during DNA replication. Recent studies have shown that telomeres function to aid in its own stability. Telomeric repeat-containing RNA (TERRA) are transcripts derived from telomeres. TERRA has been shown to maintain ...
The poly-A tail is used in the initiation of translation and also seems to have an effect on the long-term stability (aging) of the mRNA. An unnamed region after the poly-A tail, but before the actual site for transcription termination, is spliced off during transcription, and so does not become part of the 3' UTR. Its function, if any, is unknown.
In contrast, germ line and cancer cells possess an enzyme, telomerase, which prevents telomere degradation and maintains telomere integrity, causing these types of cells to be very long-lived. In humans, the role of subtelomere disorders is demonstrated in facioscapulohumeral muscular dystrophy (FSHD), Alzheimer's disease , epilepsy [ 17 ] and ...