Telomeres

Definition

Telomeres are repetitive nucleotide sequences located at the ends of linear chromosomes, protecting them from deterioration or fusion with neighboring chromosomes. These structures play a critical role in maintaining genomic stability, ensuring that the essential coding regions of DNA are preserved during cell division. As cells divide, telomeres shorten, which is a key factor in the aging process and cellular senescence.

5 Must Know Facts For Your Next Test

1. Telomeres consist of repetitive sequences, usually made up of TTAGGG in vertebrates, which protect the chromosome from degradation during replication.
2. Every time a cell divides, its telomeres shorten; when they become too short, the cell can no longer divide and may enter senescence or undergo apoptosis.
3. Telomerase is highly active in stem cells and cancer cells, allowing them to maintain telomere length and continue dividing beyond normal limits.
4. Shortened telomeres have been associated with age-related diseases such as cardiovascular disease, diabetes, and some types of cancer.
5. The study of telomeres has implications for understanding aging, cancer biology, and potential therapeutic approaches aimed at extending cellular lifespan.

Review Questions

• Explain how telomeres contribute to chromosome stability during cell division.
  • Telomeres protect the ends of chromosomes from degradation and prevent them from fusing with other chromosomes during cell division. Each time a cell divides, the DNA replication machinery struggles to fully replicate the ends of linear chromosomes, leading to telomere shortening. This protective mechanism ensures that important coding regions of DNA are not lost during replication, maintaining genomic stability as cells undergo division.
• Discuss the role of telomerase in cellular aging and its potential implications for cancer treatment.
  • Telomerase adds repetitive sequences to the ends of telomeres, counteracting their natural shortening during cell division. In normal somatic cells, telomerase activity is low or absent, leading to aging as cells reach their limit on divisions. However, in many cancer cells, telomerase is reactivated, allowing them to maintain long telomeres and divide uncontrollably. Understanding how to manipulate telomerase activity could lead to new treatments that target cancer while also addressing age-related diseases.
• Analyze the connection between shortened telomeres and age-related diseases, considering both biological mechanisms and potential therapies.
  • Shortened telomeres are linked to age-related diseases because they signal cellular senescence, where cells lose their ability to divide and function properly. This process can lead to tissue dysfunction and contribute to conditions like heart disease and diabetes. Potential therapies targeting telomerase or enhancing telomere maintenance may offer ways to mitigate these effects by promoting healthier cellular function and longevity. Research in this area could open avenues for new treatments that address both aging and related diseases.

Related terms

Chromosomes: Thread-like structures composed of DNA and proteins that contain genetic information and are found in the nucleus of eukaryotic cells.

Telomerase: An enzyme that adds repetitive nucleotide sequences to the ends of telomeres, extending their length and helping maintain chromosome stability.

Cellular Senescence: A state in which cells cease to divide and grow, often resulting from critically shortened telomeres and contributing to aging and tissue dysfunction.