Telomeres

Definition

Telomeres are repetitive DNA sequences located at the ends of linear chromosomes that protect them from degradation and fusion with neighboring chromosomes. They play a crucial role in maintaining genomic stability by preventing the loss of important genetic information during cell division, as DNA replication cannot fully replicate the very ends of chromosomes. As cells divide, telomeres shorten, which is linked to aging and cell senescence.

5 Must Know Facts For Your Next Test

1. Telomeres are composed of repeated nucleotide sequences, typically consisting of thousands of tandem repeats of the sequence 'TTAGGG' in vertebrates.
2. Every time a somatic cell divides, telomeres become shorter due to the inability of DNA polymerase to completely replicate the ends of linear chromosomes.
3. Telomerase is an enzyme that can add repetitive nucleotide sequences to telomeres, helping maintain their length, especially in stem cells and certain cancer cells.
4. Shortened telomeres are associated with cellular aging and have been implicated in age-related diseases such as cancer and cardiovascular disease.
5. Research suggests that lifestyle factors such as stress, smoking, and obesity can accelerate telomere shortening, while exercise and a healthy diet may help preserve telomere length.

Review Questions

• How do telomeres contribute to chromosome stability during cell division?
  • Telomeres play a vital role in chromosome stability by providing a protective cap at the ends of chromosomes. This protection prevents the chromosome ends from being recognized as broken DNA that needs repair, thereby avoiding unwanted fusion with other chromosomes. During DNA replication, since the enzyme cannot fully replicate the ends, telomeres ensure that essential genetic information is not lost in the process, which is critical for maintaining genomic integrity as cells divide.
• Discuss the implications of telomere shortening in relation to aging and cellular health.
  • Telomere shortening has significant implications for aging and cellular health because it limits the number of times a somatic cell can divide. As telomeres become critically short, cells enter a state called senescence where they stop dividing, leading to tissue dysfunction and contributing to age-related decline. This shortening is also linked to various diseases, including cancer, where some cells may bypass this limit through upregulation of telomerase, allowing them to proliferate uncontrollably.
• Evaluate how external factors influence telomere length and what this suggests about health management.
  • External factors like stress, diet, exercise, and lifestyle choices can significantly influence telomere length. For example, chronic stress and unhealthy habits such as smoking have been associated with accelerated telomere shortening. In contrast, engaging in regular physical activity and maintaining a balanced diet may help preserve telomere length. This understanding suggests that proactive health management strategies aimed at reducing stress and promoting healthy living could be vital for maintaining cellular health and possibly slowing down the aging process.

Related terms

Chromosome: A structure made of DNA and proteins that contains genetic information organized in a linear form.

DNA Replication: The process by which a cell duplicates its DNA before cell division, ensuring that each daughter cell receives an exact copy.

Senescence: A state in which a cell stops dividing and enters a phase of growth arrest, often associated with aging and telomere shortening.