Telomeres

Definition

Telomeres are repetitive nucleotide sequences located at the ends of linear chromosomes that protect them from deterioration or fusion with neighboring chromosomes. They play a crucial role in maintaining genomic stability by preventing the loss of important DNA during cell division. Telomeres are essential for cellular aging and have significant implications in cancer biology, as their length can influence cellular senescence and the ability of cells to proliferate.

5 Must Know Facts For Your Next Test

1. Telomeres shorten with each cell division, which is a key factor in the aging process and limits the number of times a normal somatic cell can divide.
2. In humans, telomeres consist of repetitive sequences that include the nucleotides TTAGGG, repeated about 2,500 times in newborns.
3. When telomeres become critically short, they trigger a DNA damage response that leads to cell senescence or apoptosis (programmed cell death).
4. Cancer cells often express telomerase, which allows them to maintain telomere length and divide indefinitely, contributing to tumor growth.
5. Research into telomeres has implications for aging, cancer therapy, and regenerative medicine, as manipulating telomere length may enhance tissue repair and longevity.

Review Questions

• How do telomeres function in protecting chromosome integrity during cell division?
  • Telomeres serve as protective caps at the ends of chromosomes, preventing them from being recognized as broken DNA strands. As cells divide, the replication process cannot fully copy the ends of linear chromosomes, leading to the progressive shortening of telomeres. This shortening acts as a biological clock, ensuring that cells eventually cease to divide once telomeres reach a critical length, thus preserving genomic integrity by preventing chromosomal fusion or loss.
• Discuss the role of telomerase in cancer cells and how it differs from its function in normal somatic cells.
  • Telomerase is typically inactive in most normal somatic cells, leading to progressive telomere shortening with each division. However, many cancer cells reactivate telomerase, allowing them to maintain their telomere length despite extensive cell division. This reactivation enables cancer cells to bypass the normal limits on proliferation and contributes to tumor growth by allowing these cells to divide indefinitely without entering senescence.
• Evaluate the potential implications of telomere research for therapies targeting aging and cancer treatment.
  • Research on telomeres opens up possibilities for innovative therapies aimed at aging and cancer. By understanding the mechanisms that regulate telomere length and function, scientists can develop strategies to slow down cellular aging or enhance regenerative capacities in tissues. Additionally, targeting telomerase activity in cancer cells presents a promising avenue for therapeutic intervention, potentially limiting tumor growth by inducing senescence or apoptosis in these unchecked proliferating cells. This approach could lead to more effective cancer treatments that specifically target the unique properties of cancer cell biology.

Related terms

Chromosomes: Structures within cells that contain DNA and proteins, organizing genetic material for cell division and gene expression.

Telomerase: An enzyme that adds repetitive nucleotide sequences to telomeres, helping to maintain their length and allowing certain cells, like stem cells and cancer cells, to divide indefinitely.

Senescence: A state in which cells stop dividing and enter a period of permanent growth arrest, often linked to telomere shortening.