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Subtelomeric Regions
Subtelomeres are segments of DNA between telomeric caps and chromatin. Structure Telomeres are specialized protein–DNA constructs present at the ends of eukaryotic chromosomes, which prevent them from degradation and end-to-end chromosome, chromosomal fusion. Most vertebrate telomeric DNA consists of long (Thymine, TThymine, TAdenine, AGuanine, GGuanine, GGuanine, G)n repeats of variable length, often around 3-20kb. ''Subtelomeres'' are segments of DNA between telomeric caps and chromatin. In vertebrates, each chromosome has two subtelomeres immediately adjacent to the long (TTAGGG)n repeats. Subtelomeres are considered to be the most distal (farthest from the centromere) region of unique DNA on a chromosome, and they are unusually dynamic and variable mosaics of multichromosomal blocks of sequence. The subtelomeres of such diverse species as humans, ''Plasmodium falciparum'', ''Drosophila melanogaster'', and ''Saccharomyces cerevisiae'' are structurally similar in that they ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telomere
A telomere (; ) is a region of repetitive nucleotide sequences associated with specialized proteins at the ends of linear chromosomes. Although there are different architectures, telomeres, in a broad sense, are a widespread genetic feature most commonly found in eukaryotes. In most, if not all species possessing them, they protect the terminal regions of chromosomal DNA from progressive degradation and ensure the integrity of linear chromosomes by preventing DNA repair systems from mistaking the very ends of the DNA strand for a double-strand break. Discovery In the early 1970s, Soviet theorist Alexei Olovnikov first recognized that chromosomes could not completely replicate their ends; this is known as the "end replication problem". Building on this, and accommodating Leonard Hayflick's idea of limited somatic cell division, Olovnikov suggested that DNA sequences are lost every time a cell replicates until the loss reaches a critical level, at which point cell division end ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
