Telomeres

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Telomeres

Telomeres (/tɛˈlɒmɪərz/, from the Greek telos "end" and meros "part") are a region of repetitive nucleotide sequences at each end of a chromosome, which protect the end of the chromosome from deterioration or from fusion with neighboring chromosomes.

Function

Their presence is essential for the preservation of genetic information and chromosome stability. During DNA replication, the enzymes that duplicate DNA cannot continue their duplication all the way to the end of a chromosome, so in each duplication the end of the chromosome is shortened. The telomeres are disposable buffers blocking the ends of the chromosomes and are consumed during cell division and replenished by an enzyme, the telomerase reverse transcriptase.

Telomerase

Telomerase is a ribonucleoprotein that adds a species-dependent telomere repeat sequence to the 3' end of telomeres. A deficiency in telomerase can lead to telomere shortening and can limit cell division. This limitation is known as the Hayflick limit, after the scientist who discovered it, Leonard Hayflick.

Role in Aging and Cancer

Telomeres play a key role in the process of cellular aging and cancer. As the telomeres become shorter, the cell's ability to divide is impaired, eventually causing cell death. This process is associated with aging. On the other hand, in cancer cells, telomerase is often activated, allowing these cells to divide indefinitely.

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