Telomerase enzyme

Definition

Telomerase is a specialized enzyme that adds repetitive nucleotide sequences to the ends of chromosomes, known as telomeres, thereby extending their length and preventing cellular aging. This enzyme is crucial for maintaining the stability of chromosomes during cell division, particularly in stem cells and cancer cells, where its activity allows for continued proliferation.

5 Must Know Facts For Your Next Test

1. Telomerase is typically active in germ cells, stem cells, and many cancer cells, allowing these cells to bypass the normal limits on cellular replication.
2. In most somatic cells, telomerase activity is low or absent, leading to progressive shortening of telomeres with each cell division, which contributes to aging.
3. Telomerase is made up of two main components: a reverse transcriptase enzyme that synthesizes DNA from an RNA template and an RNA component that serves as the template for telomere elongation.
4. The reactivation of telomerase is a common feature in many types of cancer, contributing to the immortality of cancer cells by preventing telomere shortening.
5. Research on telomerase inhibitors is ongoing as a potential therapeutic approach to target cancer cells that rely on this enzyme for unchecked growth.

Review Questions

• How does telomerase contribute to cellular aging and proliferation in normal versus cancer cells?
  • In normal somatic cells, telomerase activity is usually low or nonexistent, causing telomeres to shorten with each division until the cell undergoes senescence or apoptosis. In contrast, cancer cells often reactivate telomerase, allowing them to maintain their telomere length and evade the usual limits on replication. This reactivation enables cancer cells to proliferate indefinitely, contributing to tumor growth and resistance to cell death.
• Discuss the implications of telomerase activity in the development of cancer and potential therapeutic strategies targeting this enzyme.
  • Telomerase activity plays a significant role in cancer development by enabling tumor cells to escape replicative senescence. As many tumors reactivate telomerase, targeting this enzyme presents a promising strategy for cancer treatment. Inhibitors that block telomerase activity could potentially limit the ability of cancer cells to divide indefinitely and promote their eventual death. Ongoing research focuses on developing these inhibitors and understanding their efficacy in different cancer types.
• Evaluate the relationship between telomere length, telomerase activity, and the concepts of cellular immortality and organismal aging.
  • The relationship between telomere length and telomerase activity is central to understanding both cellular immortality and organismal aging. In organisms, shortening telomeres signal aging and lead to cellular senescence. However, in certain cells like stem cells and many cancerous tissues, active telomerase maintains telomere length, granting these cells the ability to divide indefinitely. This imbalance creates a dichotomy where normal aging occurs alongside the uncontrolled growth seen in tumors. This connection raises significant questions about how interventions targeting telomerase might influence both aging processes and cancer therapies.

Related terms

Telomeres: Telomeres are repetitive DNA sequences located at the ends of linear chromosomes that protect them from degradation and prevent fusion with neighboring chromosomes.

Apoptosis: Apoptosis is the process of programmed cell death that eliminates damaged or unnecessary cells, which can be disrupted in cancerous tissues.

Oncogenes: Oncogenes are mutated genes that have the potential to cause normal cells to become cancerous, often through mechanisms that involve uncontrolled cell growth and division.