A terminal section of a chromosome which has a specialized structure and which is involved in chromosomal replication and stability. Its length is believed to be a few hundred base pairs.
DNA sequences, that do not code for proteins, which are located at the (end) tips of chromosomes. Telomeres consist of the sequence GGGGTT repeated many times. With the exception of certain types of cells (e.g., zygotes, cancerous cells, “immortal” hybridoma cells), portions of each telomere “break off” each time that the cell containing that chromosome divides. This “shortening” process serves to limit the lifetime (i.e., number of replications) of those (noncancerous, nonzygote, nonhybridoma, etc.) cells.
The structures at the ends of the chromosomes.
A repetitive segment of DNA found on the ends of chromosomes. With each mitotic division, parts of the telomeres of a chromosome are lost. A theory of cellular aging proposes that the telomeres act as a biological clock and that when they are depleted, the cell dies or becomes much less active.