A telomere is a region of repetitive nucleotide sequences (a compound structure) at each end of a chromosome, which protects the end of the chromosome from deterioration or from fusion with neighboring chromosomes. Telomeres function to protect the ends of chromosomes from sticking to each other. They also protect genetic information during cell division because a short piece of each chromosome is lost every time DNA is replicated. Cells use a special enzyme called telomerase to keep dividing, which lengthens their telomeres.

Experts note that in humans the telomere sequence is TTAGGG. This sequence is usually repeated about 3,000 times and can reach up to 15,000 base pairs in length.

Besides protecting the ends of human chromosomes by forming a cap, two other major functions occur. Telomeres (1) help to organise each of the 46 chromosomes in the nucleus of a human being (the control center of human cells), and (2) allow each human chromosome to be replicated properly during cell division. Without telomeres, important DNA would be lost every time a cell divides (usually about 50 to 70 times).

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