telomere maintenance via semi-conservative replication

Definition

Target type: biologicalprocess

The process in which telomeric DNA is synthesized semi-conservatively by the conventional replication machinery and telomeric accessory factors as part of cell cycle DNA replication. [GOC:BHF, GOC:BHF_telomere, GOC:rl, GOC:vw, PMID:16598261]

Telomere maintenance through semi-conservative replication is a critical process for maintaining genomic integrity and preventing cellular senescence. Telomeres, the protective caps at the ends of chromosomes, are composed of repetitive DNA sequences and associated proteins. During DNA replication, the lagging strand is synthesized discontinuously in short fragments called Okazaki fragments. This process requires a primer to initiate synthesis, which is removed by an exonuclease. However, at the very end of the chromosome, there is no space for a primer to bind, leading to a shortening of the lagging strand with each round of replication. This is known as the end-replication problem. To overcome this problem, telomeres are maintained by a specialized enzyme called telomerase. Telomerase contains a reverse transcriptase activity that uses an internal RNA template to add telomeric repeats to the ends of chromosomes. This process extends the lagging strand, compensating for the loss of DNA during replication. The addition of telomeric repeats by telomerase ensures that the protective caps at the ends of chromosomes are maintained, preventing degradation and fusion of chromosomes. This process of telomere maintenance is crucial for cell viability and can contribute to cell immortality in certain cell types, such as germ cells and cancer cells. The regulation of telomerase activity is tightly controlled, with its expression being limited in most somatic cells. This ensures that cells have a limited lifespan and prevents uncontrolled cell division, which could lead to cancer. In summary, semi-conservative replication, coupled with telomerase activity, maintains telomere length, preventing chromosome degradation and contributing to genomic stability. This process is essential for preserving the integrity of the genome and maintaining cellular function.'
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Proteins (6)

Compounds (5)