Telomerase

Definition

Telomerase is an enzyme that adds repetitive nucleotide sequences to the ends of chromosomes, known as telomeres, helping to maintain their length and integrity during DNA replication. This process is crucial because, during cell division, chromosomes can shorten, which can lead to genetic instability and aging. Telomerase is especially active in stem cells and cancer cells, allowing these cells to replicate indefinitely.

5 Must Know Facts For Your Next Test

1. Telomerase adds a specific repeat sequence, typically TTAGGG in humans, to the 3' end of telomeres, counteracting the shortening that occurs during DNA replication.
2. Most somatic (body) cells do not express telomerase, leading to gradual telomere shortening with each cell division, which contributes to aging.
3. In stem cells and germ cells, telomerase is highly active, allowing these cells to maintain their telomere length and proliferate without limit.
4. Cancer cells often reactivate telomerase, which enables them to evade normal cellular aging processes and continue dividing uncontrollably.
5. The study of telomerase has implications for aging research and cancer therapies, as manipulating its activity could potentially lead to novel treatments for age-related diseases and cancer.

Review Questions

• How does telomerase function in maintaining chromosomal integrity during DNA replication?
  • Telomerase functions by adding repetitive nucleotide sequences to the ends of chromosomes, specifically to the telomeres. This addition prevents the shortening of telomeres that typically occurs during DNA replication due to the inability of DNA polymerase to fully replicate the ends of linear chromosomes. By maintaining telomere length, telomerase helps ensure chromosomal integrity and stability throughout multiple rounds of cell division.
• What role does telomerase play in the context of cancer biology and cellular immortality?
  • In cancer biology, telomerase is often reactivated, allowing cancer cells to bypass the normal limits on cell division associated with telomere shortening. This reactivation contributes to the phenomenon known as cellular immortality, where cancer cells can replicate indefinitely. Understanding this mechanism has significant implications for developing targeted therapies that could inhibit telomerase activity in tumors, potentially leading to more effective cancer treatments.
• Evaluate the potential therapeutic applications of targeting telomerase in age-related diseases and cancer treatment.
  • Targeting telomerase presents promising therapeutic applications in both age-related diseases and cancer treatment. In age-related conditions, inhibiting telomerase could slow down or reverse cellular senescence by promoting normal telomere shortening, thereby restoring tissue function. Conversely, in cancer treatment, developing drugs that inhibit telomerase could limit the proliferative capacity of tumor cells. Balancing these strategies requires careful consideration of how manipulating telomerase affects normal versus malignant cells, emphasizing the need for precise approaches in therapy development.

Related terms

Telomeres: Telomeres are repetitive DNA sequences located at the ends of chromosomes that protect them from degradation and prevent the loss of important genetic information during DNA replication.

DNA Replication:

DNA replication is the biological process of producing two identical replicas of a DNA molecule from a single original DNA molecule, essential for cell division.

Senescence: Senescence is the process by which cells cease to divide and grow, often as a result of telomere shortening, contributing to aging and the eventual loss of tissue function.