How does telomerase prevent linear chromosomes from shortening during replication?

Telomeres are repetitive nucleotide sequences located at the ends of linear chromosomes. They protect the chromosome from deterioration or fusion with neighboring chromosomes. During DNA replication, the enzymes that replicate DNA cannot fully replicate the ends of linear chromosomes, leading to gradual shortening with each cell division. Telomeres act as a buffer zone, ensuring that essential genetic information is not lost.

DNA replication is the biological process by which a cell duplicates its DNA before cell division. This process involves unwinding the double helix and synthesizing new strands complementary to the original ones. However, due to the nature of DNA polymerase, the enzyme responsible for replication, the very ends of linear chromosomes cannot be fully copied, resulting in the progressive shortening of telomeres with each replication cycle.

Telomerase is an enzyme that adds repetitive nucleotide sequences to the ends of telomeres, counteracting the shortening that occurs during DNA replication. It is composed of a protein component and an RNA template that guides the addition of telomeric repeats. Telomerase is particularly active in stem cells and cancer cells, allowing them to maintain telomere length and continue dividing, which is crucial for their longevity and proliferation.